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  • Strange Recurrent Excessive I/O Wait

    - by Chris
    I know quite well that I/O wait has been discussed multiple times on this site, but all the other topics seem to cover constant I/O latency, while the I/O problem we need to solve on our server occurs at irregular (short) intervals, but is ever-present with massive spikes of up to 20k ms a-wait and service times of 2 seconds. The disk affected is /dev/sdb (Seagate Barracuda, for details see below). A typical iostat -x output would at times look like this, which is an extreme sample but by no means rare: iostat (Oct 6, 2013) tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16.00 0.00 156.00 9.75 21.89 288.12 36.00 57.60 5.50 0.00 44.00 8.00 48.79 2194.18 181.82 100.00 2.00 0.00 16.00 8.00 46.49 3397.00 500.00 100.00 4.50 0.00 40.00 8.89 43.73 5581.78 222.22 100.00 14.50 0.00 148.00 10.21 13.76 5909.24 68.97 100.00 1.50 0.00 12.00 8.00 8.57 7150.67 666.67 100.00 0.50 0.00 4.00 8.00 6.31 10168.00 2000.00 100.00 2.00 0.00 16.00 8.00 5.27 11001.00 500.00 100.00 0.50 0.00 4.00 8.00 2.96 17080.00 2000.00 100.00 34.00 0.00 1324.00 9.88 1.32 137.84 4.45 59.60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 22.00 44.00 204.00 11.27 0.01 0.27 0.27 0.60 Let me provide you with some more information regarding the hardware. It's a Dell 1950 III box with Debian as OS where uname -a reports the following: Linux xx 2.6.32-5-amd64 #1 SMP Fri Feb 15 15:39:52 UTC 2013 x86_64 GNU/Linux The machine is a dedicated server that hosts an online game without any databases or I/O heavy applications running. The core application consumes about 0.8 of the 8 GBytes RAM, and the average CPU load is relatively low. The game itself, however, reacts rather sensitive towards I/O latency and thus our players experience massive ingame lag, which we would like to address as soon as possible. iostat: avg-cpu: %user %nice %system %iowait %steal %idle 1.77 0.01 1.05 1.59 0.00 95.58 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdb 13.16 25.42 135.12 504701011 2682640656 sda 1.52 0.74 20.63 14644533 409684488 Uptime is: 19:26:26 up 229 days, 17:26, 4 users, load average: 0.36, 0.37, 0.32 Harddisk controller: 01:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 04) Harddisks: Array 1, RAID-1, 2x Seagate Cheetah 15K.5 73 GB SAS Array 2, RAID-1, 2x Seagate ST3500620SS Barracuda ES.2 500GB 16MB 7200RPM SAS Partition information from df: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdb1 480191156 30715200 425083668 7% /home /dev/sda2 7692908 437436 6864692 6% / /dev/sda5 15377820 1398916 13197748 10% /usr /dev/sda6 39159724 19158340 18012140 52% /var Some more data samples generated with iostat -dx sdb 1 (Oct 11, 2013) Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sdb 0.00 15.00 0.00 70.00 0.00 656.00 9.37 4.50 1.83 4.80 33.60 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 12.00 836.00 500.00 100.00 sdb 0.00 0.00 0.00 3.00 0.00 32.00 10.67 9.96 1990.67 333.33 100.00 sdb 0.00 0.00 0.00 4.00 0.00 40.00 10.00 6.96 3075.00 250.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 2.62 4648.00 500.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 1.00 0.00 16.00 16.00 1.69 7024.00 1000.00 100.00 sdb 0.00 74.00 0.00 124.00 0.00 1584.00 12.77 1.09 67.94 6.94 86.00 Characteristic charts generated with rrdtool can be found here: iostat plot 1, 24 min interval: http://imageshack.us/photo/my-images/600/yqm3.png/ iostat plot 2, 120 min interval: http://imageshack.us/photo/my-images/407/griw.png/ As we have a rather large cache of 5.5 GBytes, we thought it might be a good idea to test if the I/O wait spikes would perhaps be caused by cache miss events. Therefore, we did a sync and then this to flush the cache and buffers: echo 3 > /proc/sys/vm/drop_caches and directly afterwards the I/O wait and service times virtually went through the roof, and everything on the machine felt like slow motion. During the next few hours the latency recovered and everything was as before - small to medium lags in short, unpredictable intervals. Now my question is: does anybody have any idea what might cause this annoying behaviour? Is it the first indication of the disk array or the raid controller dying, or something that can be easily mended by rebooting? (At the moment we're very reluctant to do this, however, because we're afraid that the disks might not come back up again.) Any help is greatly appreciated. Thanks in advance, Chris. Edited to add: we do see one or two processes go to 'D' state in top, one of which seems to be kjournald rather frequently. If I'm not mistaken, however, this does not indicate the processes causing the latency, but rather those affected by it - correct me if I'm wrong. Does the information about uninterruptibly sleeping processes help us in any way to address the problem? @Andy Shinn requested smartctl data, here it is: smartctl -a -d megaraid,2 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:13 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 20 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 1236631092 Blocks received from initiator = 1097862364 Blocks read from cache and sent to initiator = 1383620256 Number of read and write commands whose size <= segment size = 531295338 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36556.93 number of minutes until next internal SMART test = 32 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 509271032 47 0 509271079 509271079 20981.423 0 write: 0 0 0 0 0 5022.039 0 verify: 1870931090 196 0 1870931286 1870931286 100558.708 0 Non-medium error count: 0 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36538 - [- - -] # 2 Background short Completed 16 36514 - [- - -] # 3 Background short Completed 16 36490 - [- - -] # 4 Background short Completed 16 36466 - [- - -] # 5 Background short Completed 16 36442 - [- - -] # 6 Background long Completed 16 36420 - [- - -] # 7 Background short Completed 16 36394 - [- - -] # 8 Background short Completed 16 36370 - [- - -] # 9 Background long Completed 16 36364 - [- - -] #10 Background short Completed 16 36361 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes] smartctl -a -d megaraid,3 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:26 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 19 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 288745640 Blocks received from initiator = 1097848399 Blocks read from cache and sent to initiator = 1304149705 Number of read and write commands whose size <= segment size = 527414694 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36596.83 number of minutes until next internal SMART test = 28 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 610862490 44 0 610862534 610862534 20470.133 0 write: 0 0 0 0 0 5022.480 0 verify: 2861227413 203 0 2861227616 2861227616 100872.443 0 Non-medium error count: 1 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36580 - [- - -] # 2 Background short Completed 16 36556 - [- - -] # 3 Background short Completed 16 36532 - [- - -] # 4 Background short Completed 16 36508 - [- - -] # 5 Background short Completed 16 36484 - [- - -] # 6 Background long Completed 16 36462 - [- - -] # 7 Background short Completed 16 36436 - [- - -] # 8 Background short Completed 16 36412 - [- - -] # 9 Background long Completed 16 36404 - [- - -] #10 Background short Completed 16 36401 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes]

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  • How to Save Hundreds or Thousands of Dollars on Cell Phone Service

    - by Chris Hoffman
    Cell phone contracts are bad. You get a seemingly cheap phone up front, but you more than pay for the cost of the phone over two years. Prepaid phone plans are surging in North America for a reason. Prepaid phone plans will be cheaper and more flexible than traditional contracts with big carriers for many people. However much you use your phone, there’s a good chance you can save money with a prepaid service. No More Contracts Here’s how cell phone service typically works in North America: You get a subsidized phone for “free”, $99, or $199. You sign up for a two-year contract and more than pay back the cost of that phone over the length of the contract. This is similar to leasing something or purchasing it on a credit card and paying it back over two years — you spend less up front, but you’re paying more in the long run. But this isn’t the only option. You could opt for a cheaper prepaid service that doesn’t lock you into a contract. If you don’t use your phone much, you could just pay for what you use and avoid the hefty cell phone bills. If you use your phone a lot, you could get a cheaper plan, too. Now, this certainly isn’t for everyone. If you want the latest iPhone or Galaxy smartphone every two years and require a 4G data connection, prepaid services may not be for you. On the other hand, if you don’t need the latest phone, you can save money here. You can also save a huge amount of money if you don’t use your phone much. Phone Options When you choose your prepaid or contract-free service, you’ll often be able to purchase a phone from them. You’ll generally be able to find dirt-cheap dumbphones and the cheapest, slowest Android phones for not very much money. If you are able to buy a top-of-the-line smartphone, you’ll have to pay the full, unsubsidized price. That’s $649 for either an iPhone 5S or Samsung Galaxy S4. Whatever phones the service provider offers, you could always buy a phone elsewhere — for example, you could buy an unsubsidized iPhone direct from Apple and then take it to your cell phone service of choice. Most services will allow you to get a SIM card and pop it into your existing phone rather than purchasing a phone. If you can get a hand-me-down smartphone, you can often save quite a bit of money. For example, you may have a family member upgrading from an iPhone 4S to an iPhone 5S. You could take their phone to a prepaid carrier and have a nicer phone on a cheap cell phone plan. If you brought an old smartphone to a big carrier like AT&T or Verizon, they wouldn’t give you a discount on your monthly plan. You’d have to pay the same amount of money every month as if you had gotten a subsidized phone. Google’s Nexus phones are also great options for people looking to buy smartphones and pay up-front. Google’s Nexus 4 offered a modern, almost top-of-the-line Android smartphone experience at $299 or $349 when it came out last year. Google will soon be releasing the Nexus 5 and it’s expected to be priced at $349. That’s certainly a lot more than a cheap phone, but it’s a fairly high-end smartphone at almost half the price of an iPhone 5S or Galaxy S4. Nexus phones can be purchased online from Google’s Play Store. Service Options When choosing a service, you need to consider what you actually use. If you’re someone who only uses your phone rarely, you can get plans that will allow you to pay as little as a few dollars per month. If you’re someone who’s usually in range of Wi-Fi, you may not need much data at all. If you want a plan with unlimited talk, texting, and data usage, you can get it for much cheaper than you’d pay on a major carrier like AT&T. The options here range from pay-as-you-go plans, like the ones offered by T-Mobile, which allow you to put a certain amount of money in and only drain that balance when you actually use minutes, texts, or data. If you only make a few calls and send a few texts per month, you’d only pay a few bucks. On the other end, Walmart’s Straight Talk service is a popular option that offers unlimited talk, texting, and data at $45 per month. Which service is right for you depends on a lot of things, including your usage and what each network’s coverage is like in your area. You’ll want to do some research of your own before choosing a service. Prepaid services also offer you even more flexibility after you choose one. If you’re not happy or a better deal comes along, you can switch — you’re not locked into your service for two years and you won’t pay an early termination fee. Image Credit: Intel Free Press on Flickr, Jon Fingas on Flickr, John Karakatsanis on Flickr, kendalkinggroup on Flickr     

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  • Computing a normal matrix in conjunction with gluLookAt

    - by Chris Smith
    I have a hand-rolled camera class that converts yaw, pitch, and roll angles into a forward, side, and up vector suitable for calling gluLookAt. Using this camera class I can modify the model-view matrix to move about the 3D world just fine. However, I am having trouble when using this camera class (and associated model-view matrix) when trying to perform directional lighting in my vertex shader. The problem is that the light direction, (0, 1, 0) for example, is relative to where the 'camera is looking' and not the actual world coordinates. (Or is this eye coordinates vs. model coordinates?) I would like the light direction to be unaffected by the camera's viewing direction. For example, when the camera is looking down the Z axis the ground is lit correctly. However, if I point the camera straight at the ground, then it goes dark. This is (I think) because the light direction is parallel with the camera's 'up' vector which is perpendicular with the ground's normal vector. I tried computing the normal matrix without taking the camera's model view into account, but then none of my objects were rotated correctly. Sorry if this sounds vague. I suspect there is a straight forward answer, but I'm not 100% clear on how the normal matrix should be used for transforming vertex normals in my vertex shader. For reference, here is pseudo code for my rendering loop: pMatrix = new Matrix(); pMatrix = makePerspective(...) mvMatrix = new Matrix() camera.apply(mvMatrix); // Calls gluLookAt // Move the object into position. mvMatrix.translatev(position); mvMatrix.rotatef(rotation.x, 1, 0, 0); mvMatrix.rotatef(rotation.y, 0, 1, 0); mvMatrix.rotatef(rotation.z, 0, 0, 1); var nMatrix = new Matrix(); nMatrix.set(mvMatrix.get().getInverse().getTranspose()); // Set vertex shader uniforms. gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, new Float32Array(pMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, new Float32Array(mvMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.nMatrixUniform, false, new Float32Array(nMatrix.getFlattened())); // ... gl.drawElements(gl.TRIANGLES, this.vertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0); And the corresponding vertex shader: // Attributes attribute vec3 aVertexPosition; attribute vec4 aVertexColor; attribute vec3 aVertexNormal; // Uniforms uniform mat4 uMVMatrix; uniform mat4 uNMatrix; uniform mat4 uPMatrix; // Varyings varying vec4 vColor; // Constants const vec3 LIGHT_DIRECTION = vec3(0, 1, 0); // Opposite direction of photons. const vec4 AMBIENT_COLOR = vec4 (0.2, 0.2, 0.2, 1.0); float ComputeLighting() { vec4 transformedNormal = vec4(aVertexNormal.xyz, 1.0); transformedNormal = uNMatrix * transformedNormal; float base = dot(normalize(transformedNormal.xyz), normalize(LIGHT_DIRECTION)); return max(base, 0.0); } void main(void) { gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0); float lightWeight = ComputeLighting(); vColor = vec4(aVertexColor.xyz * lightWeight, 1.0) + AMBIENT_COLOR; } Note that I am using WebGL, so if the anser is use glFixThisProblem(...) any pointers on how to re-implement that on WebGL if missing would be appreciated.

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  • How to Never Use iTunes With Your iPhone, iPad, or iPod Touch

    - by Chris Hoffman
    iTunes isn’t an amazing program on Windows. There was a time when Apple device users had to plug their devices into their PCs or Macs and use iTunes for device activation, updates, and syncing, but iTunes is no longer necessary. Apple still allows you to use iTunes for these things, but you don’t have to. Your iOS device can function independently from iTunes, so you should never be forced to plug it into a PC or Mac. Device Activation When the iPad first came out, it was touted as a device that could replace full PCs and Macs for people who only needed to perform light computing tasks. Yet, to set up a new iPad, users had to plug it into a PC or Mac running iTunes and use iTunes to activate the device. This is no longer necessary. With new iPads, iPhones, and iPod Touches, you can simply go through the setup process after turning on your new device without ever having to plug it into iTunes. Just connect to a Wi-Fi or cellular data network and log in with your Apple ID when prompted. You’ll still see an option that allows you to activate the device via iTunes, but this should only be necessary if you don’t have a wireless Internet connection available for your device. Operating System Updates You no longer have to use Apple’s iTunes software to update to a new version of Apple’s iOS operating system, either. Just open the Settings app on your device, select the General category, and tap Software Update. You’ll be able to update right from your device without ever opening iTunes. Purchased iTunes Media Apple allows you to easily access content you’ve purchased from the iTunes Store on any device. You don’t have to connect your device to your computer and sync via iTunes. For example, you can purchase a movie from the iTunes Store. Then, without any syncing, you can open the iTunes Store app on any of your iOS devices, tap the Purchased section, and see stuff you’ve downloaded. You can download the content right from the store to your device. This also works for apps — apps you purchase from the App Store can be accessed in the Purchased section on the App Store on your device later. You don’t have to sync apps from iTunes to your device, although iTunes still allows you to. You can even set up automatic downloads from the iTunes & App Store settings screen. This would allow you to purchase content on one device and have it automatically download to your other devices without any hassle. Music Apple allows you to re-download purchased music from the iTunes Store in the same way. However, there’s a good chance you have your own music you didn’t purchase from iTunes. Maybe you spent time ripping it all from your old CDs and you’ve been syncing it to your devices via iTunes ever since. Apple’s solution for this is named iTunes Match. This feature isn’t free, but it’s not a bad deal at all. For $25 per year, Apple allows you to upload all your music to your iCloud account. You can then access all your music from any iPhone, IPad, or iPod Touch. You can stream all your music — perfect if you have a huge library and little storage on your device — and choose which songs you want to download to your device for offline use. When you add additional music to your computer, iTunes will notice it and upload it using iTunes Match, making it available for streaming and downloading directly from your iOS devices without any syncing. This feature is named iTunes Match because it doesn’t just upload music — if Apple already has a song you upload, it will “match” your song with Apple’s copy. This means you may get higher-quality versions of your songs if you ripped them from CD at a lower bitrate. Podcasts You don’t have to use iTunes to subscribe to podcasts and sync them to your devices. Even if you have a lowly iPod Touch, you can install APple’s Podcasts app from the app store. Use it to subscribe to podcasts and configure them to automatically download directly to your device. You can use other podcast apps for this, too. Backups You can continue backing up your device’s data through iTunes, generating local backups that are stored on your computer. However, new iOS devices are configured to automatically back up their data to iCloud. This happens automatically in the background without you even having to think about it, and you can restore such backups when setting up a device simply by logging in with your Apple ID. Personal Data In the days of PalmPilots, people would use desktop programs like iTunes to sync their email, contacts, and calendar events with their mobile devices. You probably shouldn’t have to sync this data form your computer. Just sign into your email account — for example, a Gmail account — on your device and iOS will automatically pull your email, contacts, and calendar events from your associated account. Photos Rather than connecting your iOS device to your computer and syncing photos from it, you can use an app that automatically uploads your photos to a web service. Dropbox, Google+, and even Flickr all have this feature in their apps. You’ll be able to access your photos from any computer and have a backup copy without any syncing required. You may still need to use iTunes if you want to sync local music without paying for iTunes Match or copy local video files to your device. Copying large local files over is the only real scenario where you’d need iTunes. If you don’t need to copy such files over, you can go ahead and uninstall iTunes from your Windows PC if you like. You shouldn’t need it.     

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  • How To Access the Developer Options Menu and Enable USB Debugging on Android 4.2

    - by Chris Hoffman
    In Android 4.2, the Developer Options menu and USB Debugging option have been hidden. If you need to enable USB Debugging, you can access the Developer Options menu with a quick trick. The developer options aren’t just used by developers. USB Debugging is required by adb, which is used for rooting an Android device, backing it up, installing a custom ROM, taking screenshots from a computer, or doing many other things. Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It How To Delete, Move, or Rename Locked Files in Windows

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  • Alan Turing Needs Your Help

    - by Chris Massey
    Well. sort of. Clearly, you are using a computer. If you are on this site, you are probably quite familiar with computers as artifacts of our modern society. Hopefully, you are also familiar with the fact that Alan Turing, logician and mathematician extraordinaire, was instrumental in laying down the foundations of modern computer science, and did a little work to help turn the tide of WWII in the Allies' favor. Hold that thought. A phenomenal collection of Turing's papers (including his first ever...(read more)

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  • OpenGL ES Basic Fragment Shader help with transparency

    - by Chris
    I have just spent my first half hour playing with the shader language. I have modified the basic program I have which renders the texture, to allow me to colour the texture. varying vec2 texCoord; uniform sampler2D texSampler; /* Given the texture coordinates, our pixel shader grabs the corresponding * color from the texture. */ void main() { //gl_FragColor = texture2D(texSampler, texCoord); gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).xyz,1); } I have noticed how this affects my transparent textures, and I believe I am loosing the alpha channel which would explain why previously transparent area's appear totally black. If I use the following line instead, I am shown the transparent area's gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).aaa,1); How can I retain the transparency after this modification to the colour? I have seen various things about a .w property, and also luminous, but my tweaks with those and the .aaa property are not working XD

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  • How do I ban a wifi network in Network Manager?

    - by Chris Conway
    My wifi connection drops sometimes and, for some reason, Network Manager attempts to connect to my neighbor's network, which requires a password that I don't know. The network in question is not listed in the "Edit Connections..." dialog and I can find no reference to it in any configuration file, but still the password dialog pops up every time my main connection drops. Is there a way to blacklist a wireless network so that the Network Manager will never attempt to connect to it? Or, equivalently, how can I remove the configuration data that causes the Network Manager to attempt to connect to this particular network?

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  • Agile Testing Days 2012 – Day 2 – Learn through disagreement

    - by Chris George
    I think I was in the right place! During Day 1 I kept on reading tweets about Lean Coffee that has happened earlier that morning. It intrigued me and I figured in for a penny in for a pound, and set my alarm for 6:45am. Following the award night the night before, it was _really_ hard getting up when it went off, but I did and after a very early breakfast, set off for the 10 min walk to the Dorint. With Lean Coffee due to start at 07:30, I arrived at the hotel and made my way to one of the hotel bars. I soon realised I was in the right place as although the bar was empty, there was a table with post-it’s and pens! This MUST be the place! The premise of Lean Coffee is to have several small timeboxed discussions. Everyone writes down what they would like to discuss on post-its that are then briefly explained and submitted to the pile. Once everyone is done, the group dot-votes on the topics. The topics are then sorted by the dot vote counts and the discussions begin. Each discussion had 8 mins to start with, which meant it prevented the discussions getting off topic too much. After the time elapsed, the group had a vote whether to extend the discussion by a further 4 mins or move on. Several discussion were had around training, soft skills etc. The conversations were really interesting and there were quite a few good ideas. Overall it was a very enjoyable experience, certainly worth the early start! Make Melly Happy Following Lean Coffee was real coffee, and much needed that was! The first keynote of the day was “Let’s help Melly (Changing Work into Life)”by Jurgen Appelo. Draw lines to track happiness This was a very interesting presentation, and set the day nicely. The theme to the keynote was projects are about the people, more-so than the actual tasks. So he started by showing a photo of an employee ‘Melly’ who looked happy enough. He then stated that she looked happy but actually hated her job. In fact 50% of Americans hate their jobs. He went on to say that the world over 50% of people hate Americans their jobs. Jurgen talked about many ways to reduce the feedback cycle, not only of the project, but of the people management. Ideas such as Happiness doors, happiness tracking (drawing lines on a wall indicating your happiness for that day), kudo boxes (to compliment a colleague for good work). All of these (and more) ideas stimulate conversation amongst the team, lead to early detection of issues and investigation of solutions. I’ve massively simplified Jurgen’s keynote and have certainly not done it justice, so I will post a link to the video once it’s available. Following more coffee, the next talk was “How releasing faster changes testing” by Alexander Schwartz. This is a topic very close to our hearts at the moment, so I was eager to find out any juicy morsels that could help us achieve more frequent releases, and Alex did not disappoint. He started off by confirming something that I have been a firm believer in for a number of years now; adding more people can do more harm than good when trying to release. This is for a number of reasons, but just adding new people to a team at such a critical time can be more of a drain on resources than they add. The alternative is to have the whole team have shared responsibility for faster delivery. So the whole team is responsible for quality and testing. Obviously you will have the test engineers on the project who have the specialist skills, but there is no reason that the entire team cannot do exploratory testing on the product. This links nicely with the Developer Exploratory testing presented by Sigge on Day 1, and certainly something that my team are really striving towards. Focus on cycle time, so what can be done to reduce the time between dev cycles, release cycles. What’s stops a release, what delays a release? all good solid questions that can be answered. Alex suggested that perhaps the product doesn’t need to be fully tested. Doing less testing will reduce the cycle time therefore get the release out faster. He suggested a risk-based approach to planning what testing needs to happen. Reducing testing could have an impact on revenue if it causes harm to customers, so test the ‘right stuff’! Determine a set of tests that are ‘face saving’ or ‘smoke’ tests. These tests cover the core functionality of the product and aim to prevent major embarrassment if these areas were to fail! Amongst many other very good points, Alex suggested that a good approach would be to release after every new feature is added. So do a bit of work -> release, do some more work -> release. By releasing small increments of work, the impact on the customer of bugs being introduced is reduced. Red Pill, Blue Pill The second keynote of the day was “Adaptation and improvisation – but your weakness is not your technique” by Markus Gartner and proved to be another very good presentation. It started off quoting lines from the Matrix which relate to adapting, improvising, realisation and mastery. It has alot of nerds in the room smiling! Markus went on to explain how through deliberate practice ( and a lot of it!) you can achieve mastery, but then you never stop learning. Through methods such as code retreats, testing dojos, workshops you can continually improve and learn. The code retreat idea was one that interested me. It involved pairing to write an automated test for, say, 45 mins, they deleting all the code, finding a different partner and writing the same test again! This is another keynote where the video will speak louder than anything I can write here! Markus did elaborate on something that Lisa and Janet had touched on yesterday whilst busting the myth that “Testers Must Code”. Whilst it is true that to be a tester, you don’t need to code, it is becoming more common that there is this crossover happening where more testers are coding and more programmers are testing. Markus made a special distinction between programmers and developers as testers develop tests code so this helped to make that clear. “Extending Continuous Integration and TDD with Continuous Testing” by Jason Ayers was my next talk after lunch. We already do CI and a bit of TDD on my project team so I was interested to see what this continuous testing thing was all about and whether it would actually work for us. At the start of the presentation I was of the opinion that it just would not work for us because our tests are too slow, and that would be the case for many people. Jason started off by setting the scene and saying that those doing TDD spend between 10-15% of their time waiting for tests to run. This can be reduced by testing less often, reducing the test time but this then increases the risk of introduced bugs not being spotted quickly. Therefore, in comes Continuous Testing (CT). CT systems run your unit tests whenever you save some code and runs them in the background so you can continue working. This is a really nice idea, but to do this, your tests must be fast, independent and reliable. The latter two should be the case anyway, and the first is ideal, but hard! Jason makes several suggestions to make tests fast. Firstly keep the scope of the test small, secondly spin off any expensive tests into a suite which is run, perhaps, overnight or outside of the CT system at any rate. So this started to change my mind, perhaps we could re-engineer our tests, and continuously run the quick ones to give an element of coverage. This talk was very interesting and I’ve already tried a couple of the tools mentioned on our product (Mighty Moose and NCrunch). Sadly due to the way our solution is built, it currently doesn’t work, but we will look at whether we can make this work because this has the potential to be a mini-game-changer for us. Using the wrong data Gojko’s Hierarchy of Quality The final keynote of the day was “Reinventing software quality” by Gojko Adzic. He opened the talk with the statement “We’ve got quality wrong because we are using the wrong data”! Gojko then went on to explain that we should judge a bug by whether the customer cares about it, not by whether we think it’s important. Why spend time fixing issues that the customer just wouldn’t care about and releasing months later because of this? Surely it’s better to release now and get customer feedback? This was another reference to the idea of how it’s better to build the right thing wrong than the wrong thing right. Get feedback early to make sure you’re making the right thing. Gojko then showed something which was very analogous to Maslow’s heirachy of needs. Successful – does it contribute to the business? Useful – does it do what the user wants Usable – does it do what it’s supposed to without breaking Performant/Secure – is it secure/is the performance acceptable Deployable Functionally ok – can it be deployed without breaking? He then explained that User Stories should focus on change. In other words they should focus on the users needs, not the users process. Describe what the change will be, how that change will happen then measure it! Networking and Beer Following the day’s closing keynote, there were drinks and nibble for the ‘Networking’ evening. This was a great opportunity to talk to people. I find approaching strangers very uncomfortable but once again, when in Rome! Pete Walen and I had a long conversation about only fixing issues that the customer cares about versus fixing issues that make you proud of your software! Without saying much, and asking the right questions, Pete made me re-evaluate my thoughts on the matter. Clever, very clever!  Oh and he ‘bought’ me a beer! My Takeaway Triple from Day 2: release small and release often to minimize issues creeping in and get faster feedback from ‘the real world’ Focus on issues that the customers care about, not what we think is important It’s okay to disagree with someone, even if they are well respected agile testing gurus, that’s how discussion and learning happens!  

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  • How To Delete, Move, or Rename Locked Files in Windows

    - by Chris Hoffman
    Windows won’t allow you to modify files that open programs have locked. if you try to delete a file and see a message that it’s open in a program, you’ll have to unlock the file (or close the program). In some cases, it may not be clear which program has locked a file – or a background process may have locked a file and not terminated correctly. You must unlock the stubborn file or folder to modify it. Note: Unlocking certain files and deleting them may cause problems with open programs. Don’t unlock and delete files that should remain locked, including Windows system files. How To Delete, Move, or Rename Locked Files in Windows HTG Explains: Why Screen Savers Are No Longer Necessary 6 Ways Windows 8 Is More Secure Than Windows 7

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  • Do you know your ADF "grace period?"

    - by Chris Muir
    What does the term "support" mean to you in context of vendors such as Oracle giving your organization support with our products? Over the last few weeks I'm taken a straw poll to discuss this very question with customers, and I've received a wide array of answers much to my surprise (which I've paraphrased): "Support means my staff can access dedicated resources to assist them solve problems" "Support means I can call Oracle at anytime to request assistance" "Support means we can expect fixes and patches to bugs in Oracle software" The last expectation is the one I'd like to focus on in this post, keep it in mind while reading this blog. From Oracle's perspective as we're in the business of support, we in fact offer numerous services which are captured on the table in the following page. As the text under the table indicates, you should consult the relevant Oracle Lifetime Support brochures to understand the length of time Oracle will support Oracle products. As I'm a product manager for ADF that sits under the FMW tree of Oracle products, let's consider ADF in particular. The FMW brochure is found here. On page 8 and 9 you'll see the current "Application Development Framework 11gR1 (11.1.1.x)" and "Application Development Framework 11gR2 (11.1.2)" releases are supported out to 2017 for Extended Support. This timeframe is pretty standard for Oracle's current released products, though as new releases roll in we should see those dates extended. On page 8 of the PDF note the comment at the end of this page that refers to the Oracle Support document 209768.1: For more-detailed information on bug fix and patch release policies, please refer to the “Error Correction Support Policy” on MyOracle Support. This policy document is important as it introduces Oracle's Error Correction Support Policy which addresses "patches and fixes". You can find it attached the previous Oracle Support document 209768.1. Broadly speaking while Oracle does provide "generalized support" up to 2017 for ADF, the Error Correction Support Policy dictates when Oracle will provide "patches and fixes" for Oracle software, and this is where the concept of the "grace period" comes in. As Oracle releases different versions of Oracle software, say 11.1.1.4.0, you are fully supported for patches and fixes for that specific version. However when we release the next version, say 11.1.1.5.0, Oracle provides at minimum of 3 months to a maximum of 1 year "grace period" where we'll continue to provide patches and fixes for the previous version. This gives you time to move from 11.1.1.4.0 to 11.1.1.5.0 without being unsupported for patches and fixes. The last paragraph does generalize as I've attempted to highlight the concept of the grace period rather than the specific dates for any version. For specific ADF and FMW versions and their respective grace periods and when they terminated you must visit Oracle Support Note 1290894.1. I'd like to include a screenshot here of the relevant table from that Oracle Support Note but as it is will be frequently updated it's better I force you to visit that note. Be careful to heed the comment in the note: According to policy, the Grace Period has passed because a newer Patch Set has been released for more than a year. Its important to note that the Lifetime Support Policy and Error Correction Support Policy documents are the single source of truth, subject to change, and will provide exceptions when required. This My Oracle Support document is providing a summary of the Grace Period dates and time lines for planning purposes. So remember to return to the policy document for all definitions, note 1290894.1 is a summary only and not guaranteed to be up to date or correct. A last point from Oracle's perspective. Why doesn't Oracle provide patches and fixes for all releases as long as they're supported? Amongst other reasons, it's a matter of practicality. Consider JDeveloper 10.1.3 released in 2005. JDeveloper 10.1.3 is still currently supported to 2017, but since that version was released there has been just under 20 newer releases of JDeveloper. Now multiply that across all Oracle's products and imagine the number of releases Oracle would have to provide fixes and patches for, and maintain environments to test them, build them, staff to write them and more, it's simple beyond the capabilities of even a large software vendor like Oracle. So the "grace period" restricts that patches and fixes window to something manageable. In conclusion does the concept of the "grace period" matter to you? If you define support as "getting assistance from Oracle" then maybe not. But if patches and fixes are important to you, then you need to understand the "grace period" and operate within the bounds of Oracle's Error Correction Support Policy. Disclaimer: this blog post was written July 2012. Oracle Support policies do change from time to time so the emphasis is on you to double check the facts presented in this blog.

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  • 42+ Text-Editing Keyboard Shortcuts That Work Almost Everywhere

    - by Chris Hoffman
    Whether you’re typing an email in your browser or writing in a word processor, there are convenient keyboard shortcuts usable in almost every application. You can copy, select, or delete entire words or paragraphs with just a few key presses. Some applications may not support a few of these shortcuts, but most applications support the majority of them. Many are built into the standard text-editing fields on Windows and other operating systems. Image Credit: Kenny Louie on Flickr HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It HTG Explains: Learn How Websites Are Tracking You Online Here’s How to Download Windows 8 Release Preview Right Now

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  • HTG Explains: Does Your Android Phone Need an Antivirus?

    - by Chris Hoffman
    The media is full of reports saying Android malware is exploding and that Android users are at risk. Does this mean you should install an antivirus app on your Android phone or tablet? While there may be a lot of Android malware in the wild, a look at Android’s protections and studies from antivirus companies reveals that you’re probably safe if you follow some basic precautions. How To Use USB Drives With the Nexus 7 and Other Android Devices Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It

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  • How To Easily Back Up Your Gmail and Perform Scheduled Backups With GMVault

    - by Chris Hoffman
    We all know backups are important, but we rarely think about backing up our email. GMVault can automatically back up your Gmail to your computer and even restore the emails to another Gmail account – convenient when switching Gmail addresses. We’ve also covered using Thunderbird to back up your web-based email account, but GMVault has a few advantages, including its integrated restore function and easy integration with the Windows Task Scheduler. 8 Deadly Commands You Should Never Run on Linux 14 Special Google Searches That Show Instant Answers How To Create a Customized Windows 7 Installation Disc With Integrated Updates

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  • Solution for installing the ADF 11.1.1.6.0 Runtimes onto a standalone WLS 10.3.6

    - by Chris Muir
    A few customers are hitting the following problem with regards to JDeveloper 11.1.1.6.0 so it's worth documenting a solution. As noted in my previous post the ADF Runtimes for JDeveloper 11.1.1.6.0 will work against a 10.3.5 and 10.3.6 WLS server.  In terms of the JDeveloper 11.1.1.6.0 download Oracle has coupled the 10.3.5 server with that release, not a 10.3.6 server. This has caught some customers out as they are attempting to use the JDeveloper installer to load the 11.1.1.6.0 ADF Runtimes into the middleware home of a standalone 10.3.6 WLS server.  When doing so the installer complains as follows: "The product maintenance level of the current server (WebLogic Server: 10.3.5.0) is not compatible with the maintenance level of the product installed on your system (WebLogic Server: 10.3.6.0).  Please obtain a compatible installer or perform maintenance or your current system to achieve the desired level." The solution is to install the runtimes using the standalone 11.1.1.6.0 ADF Runtime Libraries installer available from OTN (see the options under "Application Development Runtime").

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  • Use Classic Shell to Get a Classic Start Menu & Explorer Toolbar in Windows 8

    - by Chris Hoffman
    Classic Shell is an open-source utility that brings classic Windows features to newer versions of Windows. It offers the most classic Start menu for Windows 8 yet, and it lets you avoid the ribbon with a Windows Explorer toolbar. We’ve also written about getting a Windows 7-style Start button with ViStart and a Metro-style Start menu with Start 8. Or, if you’re brave, dive into the deep end and try living without the Start button for a while. How to Stress Test the Hard Drives in Your PC or Server How To Customize Your Android Lock Screen with WidgetLocker The Best Free Portable Apps for Your Flash Drive Toolkit

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  • Most efficient arc for developing cross-browser support?

    - by Chris Hasbrouck
    I'm curious to hear what approach people take to planning for cross-browser support when developing a website. There are generally two approaches I've seen developers take in their workflow: -optimize for webkit then apply hacks for IE7-9, or -optimize for IE7-8 then apply newer features for IE9/webkit Basically starting at the front of technology and working toward the back, or starting at the back of technology and working toward the front. How do you do things? What advantages or disadvantage do you perceive in the different way of doing things wrt to developing cross-browser support?

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  • How can I unit test a class which requires a web service call?

    - by Chris Cooper
    I'm trying to test a class which calls some Hadoop web services. The code is pretty much of the form: method() { ...use Jersey client to create WebResource... ...make request... ...do something with response... } e.g. there is a create directory method, a create folder method etc. Given that the code is dealing with an external web service that I don't have control over, how can I unit test this? I could try and mock the web service client/responses but that breaks the guideline I've seen a lot recently: "Don't mock objects you don't own". I could set up a dummy web service implementation - would that still constitute a "unit test" or would it then be an integration test? Is it just not possible to unit test at this low a level - how would a TDD practitioner go about this?

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  • Immutable Method in Java

    - by Chris Okyen
    In Java, there is the final keyword in lieu of the const keyword in C and C++. In the latter languages there are mutable and immutable methods such as stated in the answer by Johannes Schaub - litb to the question How many and which are the uses of “const” in C++? Use const to tell others methods won't change the logical state of this object. struct SmartPtr { int getCopies() const { return mCopiesMade; } }ptr1; ... int var = ptr.getCopies(); // returns mCopiesMade and is specified that to not modify objects state. How is this performed in Java?

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  • How to Install Incompatible Android Apps from Google Play

    - by Chris Hoffman
    Some Android apps on Google Play claim to be incompatible with various devices. There’s a good chance that these apps will run fine on many of these devices – you can bypass this check with root access. Some apps won’t actually work after you install them, but many will. This also solves problems with games that will install but refuse to play – for example, Gameloft games with the “this device is incompatible” message. Hack Your Kindle for Easy Font Customization HTG Explains: What Is RSS and How Can I Benefit From Using It? HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It

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  • Recommendations for adjustable sit-stand workstations?

    - by Chris Phillips
    Recently, I've been feeling the discomfort of sitting at my desk all day long. I'm fairly active, stretch, and take regular breaks, but some days it's still pretty uncomfortable to sit all day long, whether in a nice chair or on an exercise ball. I would really like able to stand at my computer for part of the day. My current setup is a large desk with two 26" lcds and a 17" laptop. I don't mind if the laptop isn't adjustable, as I don't use it as regularly as the monitors. I would like to be able to fairly easily switch from a sitting position to a standing position and back again as necessary. I've been looking into adjustable height desks and stands and found that they tend to be either really expensive, or don't quite meet my needs. (For example, the Ergotron WorkFit-S Dual LCD workstation looks like the ideal feature set at a reasonable price, but won't fit with my monitors.) Any suggestions or thoughts? Update: fixed a typo. Thanks @RDL!

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  • How To Enable Aero Glass-Style Transparency in Windows 8

    - by Chris Hoffman
    Aero Glass is gone in Windows 8. If you really miss Aero Glass, there’s a trick you can use to re-enable the transparent window title bars and borders – although Microsoft doesn’t want us to. Microsoft has removed a lot of the code that makes Aero Glass, once an important Windows feature, possible. This trick doesn’t work perfectly – the blur effect has been removed by Microsoft and graphical corruption can occur in some situations. 6 Ways Windows 8 Is More Secure Than Windows 7 HTG Explains: Why It’s Good That Your Computer’s RAM Is Full 10 Awesome Improvements For Desktop Users in Windows 8

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  • Effective way to check if an Entity/Player enters a region/trigger

    - by Chris
    I was wondering how multiplayer games detect if you enter a special region. Let's assume there is a huge map that is so big that simply checking it would become a huge performance issue. I've seen bukkit (a modding API for Minecraft servers) firing an Event on every single move. I don't think that larger games do the same because even if you have only a few coordinates you are interested in, you have to loop through a few trigger zone to see if the player is inside your region - for every player. This seems like an extremely CPU-intense operation to me even though I've never developed something like that. Is there a special algorithm that is used by larger games to accomplish this? The only thing I could imagine is to split up the world into multiple parts and to register the event not on the movement itself but on all the parts that are covered by your area and only check for areas that are registered in the current part. And another thing I would like to know: How could you detect when someone must have entered a trigger but you never saw him directly in it since his client only sent you an move packet shortly before entering and after leaving the trigger area. Drawing a line and calculate all colliding parts seems rather CPU intensive if you have to perform it every time.

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  • How to Use Windows 8's Storage Spaces to Mirror & Combine Drives

    - by Chris Hoffman
    “Storage Spaces” is a new feature in Windows 8 that can combine multiple hard drives into a single virtual drive. It can mirror data across multiple drives for redundancy or combine multiple physical drives into a single pool of storage. You can even create pools of storage larger than the amount of physical storage space you have available. When the physical storage fills up, you can plug in another drive and take advantage of it with no additional configuration required. Storage Spaces is similar to RAID or LVM on Linux. The HTG Guide to Hiding Your Data in a TrueCrypt Hidden Volume Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos

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  • ASP.NET MVC WebService - Security for Industrial Android Clients

    - by Chris Nevill
    I'm trying to design a system that will allow a bunch of Android devices to securely log into an ASP.NET MVC REST Web service. At present neither side are implemented. However there is an ASP.NET MVC website which the web service will site along side. This is currently using forms authentication. The idea will be that the Android devices will download data from the web service and then be able to work offline storing data in their own local databases, where users will be able to make updates to that data, and then syncing updates back to the main server where possible. The web service will be using HTTPS to prevent calls being intercepted and reduce the risk of calls being intercepted. The system is an industrial system and will not be in used by the general Android population. Instead only authorized Android devices will be authorized by the Web Service to make calls. As such I was thinking of using the Android devices serial number as a username and then a generated long password which the device will be able to pick up - once the device has been authorized server side. The device will also have user logins - but these will not be to log into the web service - just the device itself - since the device and user must be able to work offline. So usernames and passwords will be downloaded and stored on the devices themselves. My question is... what form of security is best setup on the web service? Should it use forms Authentication? Should the username and password just be passed in with each GET/POST call or should it start a session as I have with the website? The Android side causes more confusion. There seems to be a number of options here Spring-Android, Volley, Retrofit, LoopJ, Robo Spice which seems to use the aforementioned Spring, Retrofit or Google HttpClient. I'm struggling to find a simple example which authenticates with a forms based authentication system. Is this because I'm going about this wrong? Is there another option that would better suite this?

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