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Articles indexed Tuesday November 12 2013

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  • When using software RAID and LVM on Linux, which IO scheduler and readahead settings are honored?

    - by andrew311
    In the case of multiple layers (physical drives - md - dm - lvm), how do the schedulers, readahead settings, and other disk settings interact? Imagine you have several disks (/dev/sda - /dev/sdd) all part of a software RAID device (/dev/md0) created with mdadm. Each device (including physical disks and /dev/md0) has its own setting for IO scheduler (changed like so) and readahead (changed using blockdev). When you throw in things like dm (crypto) and LVM you add even more layers with their own settings. For example, if the physical device has a read ahead of 128 blocks and the RAID has a readahead of 64 blocks, which is honored when I do a read from /dev/md0? Does the md driver attempt a 64 block read which the physical device driver then translates to a read of 128 blocks? Or does the RAID readahead "pass-through" to the underlying device, resulting in a 64 block read? The same kind of question holds for schedulers? Do I have to worry about multiple layers of IO schedulers and how they interact, or does the /dev/md0 effectively override underlying schedulers? In my attempts to answer this question, I've dug up some interesting data on schedulers and tools which might help figure this out: Linux Disk Scheduler Benchmarking from Google blktrace - generate traces of the i/o traffic on block devices Relevant Linux kernel mailing list thread

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  • Raid 5 GPT Partitioning

    - by user39325
    I have a Dell Poweredge r710 server with five 1 TB disks. All of them are in RAID 5. I was trying to install Centos but it says "Your boot partition is on disk using GPT Partition..." I read somewhere that centos can't install on a disk larger than 2TB, so I made some partitions smaller, but it's not working. PS, I am going to install Proxmox on that, but Proxmox also won't accept disks larger than 2TB.

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  • I do not understand -printf script

    - by jerzdevs
    I have taken over the responsibility of RHLE5 scripting and I've not had any training in this platform or BASH scripting. There's a script that has multiple pieces to it and I will ask only about the second piece but also show you the first, I think it will help with my question below. The first part of the script shows the output of users on a particular server: cut -d : -f 1 /etc/passwd The output will look something like: root bin joe rob other... The second script requires me to fill in each of the accounts listed from the above script and run. From what I can gather, and from my search on the man pages and other web searches, it goes out and finds the group owner of a file or directory and obviously sorts and picks out just unique records but not really sure - so that's my question, what does the below script really do? (The funny thing is, is that if I plug in each name from the output above, I'll sometimes receive a "cannot find username blah, blah, blah" message.) find username -printf %G | sort | uniq

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  • What happened to the ability to go back in a already-loaded YouTube video?

    - by Chelonian
    For many years, my experience with YouTube had been, consistently and on any computer/browser, that once a section of that video were loaded, or the whole video, if you wanted to see an earlier part of the video again, you could simply click on the loading bar to that area and you would instantly go to that part. More recently (6 months?) this has changed. Now, clicking in an earlier part of the video forces a reload of the whole video (that is, the grey bar goes back to 0) and you have to hope your loading will be fast enough to make waiting to watch it again even worth it. It is a huge regression in usability for me. Is there any way to watch YouTube videos in the "old way"? I use Firefox 17.0.1 at this point and have an updated (I think) Flash, but I'd be willing to try other browsers or versions if it made a difference.

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  • Ctrl-Alt-F1 never gives prompt

    - by nispio
    When I press Ctrl+Alt+F1 in my Red Hat Enterprise Linux 6.4 (Santiago) I get a black screen with a blinking cursor, but I never get a login prompt. I can get back to my desktop with Ctrl+Alt+F7, and things work as normal. However, when I run sudo init 3 I get the same thing, but this time I am stuck at the screen and can't get back without a reboot. I'm not even sure where to start looking for the cause of this problem. Are the startup scripts that might be causing the problem or other system configurations that could lead to this? If this is not an known issue, what steps should I take to debug?

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  • type mismatch errors querying data from spreadsheet

    - by user2984933
    In EXCEL 2010 I am trying to querying data in another spreadsheet. The data range in the source sheet/ file is named (DATABASE). The Date field in the database is formatted as short date and when I query the date without criteria I get a different format of European datesYYYY-MM-DD with time in the results. When I use criteria and a specific date in the date field criteria grid using English format MM-DD-YYYY I get results. When I set parameters looking at destination file cells for the date for the parameters, I get Type mismatch EVEN THOUGHT THE CELLS ARE Short date Formatted. This worked perfectly in my 2003 version of EXCEL. Now I am running Win 7 -64 and Office 2010 Pro. Why does the query throw Mismatch with cell references for the parameters but accepts hard value dates in any date format? (MSQRY32.EXE)

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  • Windows 7 boot error 0xc0000225 after falling down

    - by Hulehule20
    My Toshiba netbook fell down and hasn't booted again. When I start Windows 7 it immediately says: Windows failed to start... Status: 0xc0000225 Info: The boot selection failed because a required device is inaccessible. After that, there are a few things to consider: There's a Linux distro Linkat which is also installed in the computer. It starts normally without any problem and it doesn't seem to display any errors when it boots. I restored all computer OSs with clonezilla and some images provided by the manufacturer, and it's done nothing. I have already checked the basic components of the PC (RAM, Hard Disk, WLAN Card) are pluged in and working. My impression is that's all about some broken part inside, though the Linux OS starts normally. Does anyone know a way I can fix this or at least any software for identifying the problem at all?

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  • Connecting OS X MacBook Pro to DirecTV DVR

    - by user14293
    I have a DirecTV DVR which soon will be replaced. The local phone carrier has wired fiber-to-the-door and that DirecTV sat service will soon be history. I have irreplaceable video recordings on the DVR's disk I would like to salvage. I'd like to connect my MacBook Pro (OS X 10.5.3) to the DVR (male HDMI to male Thunderbolt) and treat the MAC as a TV monitor. I'd like to capture the video stream to a file and then burn it to DVD. This is for my use only, not for distribution. Still researching video capture. Don't yet have a solution. Maybe there isn't one. Any ideas?

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  • Can a windows virus downloaded in linux be transferred to windows?

    - by user219048
    I know that linux is mostly safe from viruses, however: if you do download a windows virus (i.e., through a drive-by download), will it just sit there on your computer, and take up space? Is it unable to infect files because of the different operating system? If you transfer files between computers (by using a usb flash drive or through online file sharing), is there any risk that the virus could be transferred to windows and activate?

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  • How does communication between 2 computers in a single network happen?

    - by learner
    Lets say I and my friend connect our computers with a LAN cable. I ping my friend with his IP address. How does it work? Since we are in the same network, we don't even need IP addresses, do we? Isn't IP addressing only relevant in case of inter-network communication? What will the ping command do with his IP address? How will it eventually find his physical address (NIC address)? (no ARP here, because that would involve a router at the edge of the network, which doesn't apply here). Am I wrong somewhere?

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  • Retrieving a virtual box vdh that has been deleted from within Virtual box itself

    - by WillNZ
    I had a MS Virtual machine that I imported to virtual box to see how it worked. I decided that in this case MS Virtual machine worked just as good so removed the virtual machine from Virtual Box. In the process I accidently removed/deleted the vhd file that MS Virtual machine uses. Can I get this back from somewhere within virtual box or the recycle bin or do I have to use a undelete utlilty?

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  • Two related cells: give a value in one, calculate the other, and vice versa?

    - by Virtlink
    How can I have a cell that uses the literal value written into it, or calculates its value when no literal value was given? For example: I have two columns: column B with a price including VAT, and column C with a price without VAT. If I put a price with VAT in B2, then I want cell C2 to calculate the price without VAT based on B2. But if I put a price without VAT in C2, then I want cell B2 to calculate the price with VAT from C2. I want to give this spreadsheet to my mother, who barely understands Excel. She just has to enter the values that she knows, and the worksheet should derive the other values from that.

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  • NVIDIA GeForce GT750M drivers for Ubuntu 13.10 on iMac

    - by Eugene B
    I have just got a new iMac 14.3 with 21.5' display. It has Intel i7 processor and NVIDIA GeForce GT750M graphics card with GPU (Device ID: 0x00fe9). I have installed Ubuntu 13.10 on it (dual boot with refit). Everything works fine apart from graphics. It is clear that graphics' not accelerated, and there are no drivers suggested in the "Additional drivers" section. I have tried to Install nvidia drivers from the repository. Download nvidia drivers and install them manually. Follow instructions here. Follow instructions here. Follow instructions here. Install bumblebee. Play around with xorg.conf file. Blacklist nouveau. As you may guess, nothing worked. The weirdest thing is, that when I boot from a LiveCD, it picks up screen resolution and all the rest correctly, though when I install the system to my Hard Drive it clearly does not have proper drivers. Does anyone have any suggestion what to do?

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  • Root cause for high CPU usage; which measurement to trust more: Windows Task Manager or Process Explorer?

    - by p.campbell
    Consider this Windows 8.1 machine (in-place upgrade from Windows 8) with differing reports on its CPU usage. The machine is idle, and has been for 3 days. There are no CPU intensive tasks running currently nor over the 3 day idle period. Windows Task Manager is reporting CPU usage constantly at an incredibly high value (and increasing over time!) at around 75%. Process Explorer from SysInternals reports that the CPU usage is much different at around 42% How does Process Explorer report 42.14% usage, but its columns report Idle at 57%, with the sum of the other processes not even approaching 10%? Which of these two values should I trust more, and why should it be trusted over the other measurement? How can I actually determine which process is causing Task Manager to report its values? These Proc Exp metrics were taken with Administrator privileges, and with option 'Show Details for All Processes' Click for larger view:

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  • Extract number with regex

    - by Joey
    I have this string: > HTTP/1.1 200 OK Date: Tue, 12 Nov 2013 15:26:17 GMT Server: > Apache/2.2.3 (CentOS) Last-Modified: Fri, 08 Nov 2013 21:34:50 GMT > ETag: "452//path/to/file" > Accept-Ranges: bytes Content-Length: 26010 Connection: close > Content-Type: text/plain; charset=UTF-8 And would like to extract 452 which is before // and after ETag, what regex to use? I am stuck. Thanks a lot

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  • Black spray (?) on a laptop's heat sink assembly

    - by arnehehe
    We have a HP Pavilion DV3 4000SB that was given an error on startup that the fan was having problems (System Fan 90b error message) So I decided to open the laptop up and clean the fan, as that seemed the easiest option. Upon opening it up, at first I froze and thought "No wonder! The whole thing's burnt!", but then I started thinking it looked more like someone used a spraycan on it. I looked up a video on youtube of someone disassembling his Pavilion and noticed there wasn't any of the black on his, so my question here is: Have any of you encountered this, or know what it is? Or if it's something that could point to a problem?

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  • Windows - Decrypt encrypted file when user account is destroyed

    - by dc2
    I have a Virtual Machine running on my Windows Server 2008 computer that originally was received by me encryped, as the builder of the VM did it on a MAC, which decrypts files by default. I never thought to decrypt these files, as they automatically 'decrypt' when you have permission over them, so the VM has been running for over a year despite the encryption. I just upgraded my computer to Domain Controller (dcpromo.exe). Now when I try to access/run the VM, I can't because I don't have permission to decrypt the files as that was on another logon (local administrator) and now I am the domain administrator. Apparently the local admin is totally nuked when you upgrade to domain controller. I have tried EVERYTHING - taking ownership of the files, which works. Doesn't do anything for me. Adding full control to everyone on the files. I go to File Properties Advanced Details (under encryption) Users who can access this file. The only user is administrator@localcomputername, and there is a cert number. I try adding a new cert, I don't have permission. I don't have permission to: Decrypt the file (access is denied). Copy the file (to another computer) - access denied. I am totally stumped and this VM is a production machine and needs to get up right now. Does anyone have any ideas?

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  • Why does my microwave kill the Wi-Fi?

    - by Ohlin
    Every time I start the microwave in the kitchen, our home Wi-Fi stops working and all devices lose connection with our router! The kitchen and the Wi-Fi router are in opposite ends of the apartment but devices are being used a little here and there. We've been annoyed by the instability of the Wi-Fi for some time and it wasn't until recently we realized it was correlated to microwave usage. After some testing with having the microwave on and off we could narrow down the problem to only occurring when the router is in b/g/n mode and uses a set channel. If I change to b/g mode or set channel to auto then there is no problem any more...but still! The router is a Zyxel P-661HNU ("802.11n Wireless ADSL2+ 4-port Security Gateway" with latest firmware) and the microwave is made by Neff with an effect of 1000W (if this information might be useful to anyone). There is an "internet connection" light on the router and it doesn't go out when the interruption occurs so I think this is only an internal Wi-Fi issue. Now to my questions: What parts of the Wi-Fi can possibly be affected by the microwave usage? Frequency? Disturbances in the electrical system? How can setting Auto on channels make a difference? I thought the different channels were just some kind of separation system within the same frequency spectrum? Could this be a sign that the microwave is malfunctioning and slowly roasting us all at home? Is there any need to be worried? Since we were able to find router settings that cooperate well with our microwave's demand for attention, this question is mainly out of curiosity. But as most people out there...I just can't help the fact that I need to know how it's possible :-)

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  • I want to remove all images from my word document without losing the data formatting

    - by Chella
    Can any body help me, in this regard. I just want to remove all the images in my word document. I have about 365 pages document, in which there are images in almost all pages. I can not delete one by one. I can save it in .txt format but I will lose the formatting of the data. Is there any other way to get this. any help would be greatly appreciated. Thanks in advance. Let me know if you people need more clarification on this.

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  • How can I export search folders in Outlook 2010?

    - by Martin
    In Outlook it is possible to export rules. Is it also possible to export custom search folders? I am trying to export the custom search folders I have defined in Outlook 2010 (the logic, not the contents). I have tried: right clicking the search folders and looking into the available menus going into the outlook Import/Export menu, but I can only export real folders to .pst etc. looked into the rules menu

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  • Toshiba Satellite P755D USB 3.0 Drivers Missing - Windows 7 Professional

    - by nicorellius
    I bought a Toshiba Satellite P755D recently and installed Windows 7 Professional on the machine. It runs great. But I noticed the exclamation point in the yellow triangle icon in the Device Manager next to the Universal Serial Buss (USB) Controller (I'm assuming this is the USB 3.0 controller because mine doesn't recognize devices). Normally, when this kind of thing happens I go to the manufacturer's website and download appropriate drivers and call it a day. But not this time... I browsed to my model and found no driver for the USB 3.0 controller. I tried other HW and Utility drivers, thinking they would be bundled. No luck. I tried looking up the motherboard in my machine. Generic name, no luck. I then called Toshiba technical support and they tried basic troubleshooting, eg, uninstall device, reboot, for auto-installation; no luck. I popped the Windows 7 disk back in and tried to get information that way, no luck. Finally, the technical support guy said he would look into the engineer's system to see if there was a specific driver available and that's where I'm at. The technician told me that these USB 3.0 drivers come within the native driver pack in windows but that doesn't seem to be the case. Any ideas? EDIT - See attached screen shots.

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  • Does Gedit have cool keyboard shortcuts?

    - by Kelp
    I have used Vim before and I love the keyboard shortcuts, but I hate having to copy and paste, so I am looking for a text editor that makes it easier. I have been trying Gedit. It's cool. But I really miss the being to create a new line, going to the end of the line, going to the beginning of the line, deleting a line with keyboard shortcuts. I tried to look up "gedit keyboard shortcuts" but all it came up with was how to save a file. Basic things.

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  • Can Google Employees See My Saved Google Chrome Passwords?

    - by Jason Fitzpatrick
    Storing your passwords in your web browser seems like a great time saver, but are the passwords secure and inaccessible to others (even employees of the browser company) when squirreled away? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader MMA is curious if Google employees have (or could have) access to the passwords he stores in Google Chrome: I understand that we are really tempted to save our passwords in Google Chrome. The likely benefit is two fold, You don’t need to (memorize and) input those long and cryptic passwords. These are available wherever you are once you log in to your Google account. The last point sparked my doubt. Since the password is available anywhere, the storage must in some central location, and this should be at Google. Now, my simple question is, can a Google employee see my passwords? Searching over the Internet revealed several articles/messages. Do you save passwords in Chrome? Maybe you should reconsider: Talks about your passwords being stolen by someone who has access to your computer account. Nothing mentioned about the central storage security and vulnerability. There is even a response from Chrome browser security tech lead about the first issue. Chrome’s insane password security strategy: Mostly along the same line. You can steal password from somebody if you have access to the computer account. How to Steal Passwords Saved in Google Chrome in 5 Simple Steps: Teaches you how to actually perform the act mentioned in the previous two when you have access to somebody else’s account. There are many more (including this one at this site), mostly along the same line, points, counter-points, huge debates. I refrain from mentioning them here, simply carry a search if you want to find them. Coming back to my original query, can a Google employee see my password? Since I can view the password using a simple button, definitely they can be unhashed (decrypted) even if encrypted. This is very different from the passwords saved in Unix-like OS’s where the saved password can never be seen in plain text. They use a one-way encryption algorithm to encrypt your passwords. This encrypted password is then stored in the passwd or shadow file. When you attempt to login, the password you type in is encrypted again and compared with the entry in the file that stores your passwords. If they match, it must be the same password, and you are allowed access. Thus, a superuser can change my password, can block my account, but he can never see my password. So are his concerns well founded or will a little insight dispel his worry? The Answer SuperUser contributor Zeel helps put his mind at ease: Short answer: No* Passwords stored on your local machine can be decrypted by Chrome, as long as your OS user account is logged in. And then you can view those in plain text. At first this seems horrible, but how did you think auto-fill worked? When that password field gets filled in, Chrome must insert the real password into the HTML form element – or else the page wouldn’t work right, and you could not submit the form. And if the connection to the website is not over HTTPS, the plain text is then sent over the internet. In other words, if chrome can’t get the plain text passwords, then they are totally useless. A one way hash is no good, because we need to use them. Now the passwords are in fact encrypted, the only way to get them back to plain text is to have the decryption key. That key is your Google password, or a secondary key you can set up. When you sign into Chrome and sync the Google servers will transmit the encrypted passwords, settings, bookmarks, auto-fill, etc, to your local machine. Here Chrome will decrypt the information and be able to use it. On Google’s end all that info is stored in its encrpyted state, and they do not have the key to decrypt it. Your account password is checked against a hash to log in to Google, and even if you let chrome remember it, that encrypted version is hidden in the same bundle as the other passwords, impossible to access. So an employee could probably grab a dump of the encrypted data, but it wouldn’t do them any good, since they would have no way to use it.* So no, Google employees can not** access your passwords, since they are encrypted on their servers. * However, do not forget that any system that can be accessed by an authorized user can be accessed by an unauthorized user. Some systems are easier to break than other, but none are fail-proof. . . That being said, I think I will trust Google and the millions they spend on security systems, over any other password storage solution. And heck, I’m a wimpy nerd, it would be easier to beat the passwords out of me than break Google’s encryption. ** I am also assuming that there isn’t a person who just happens to work for Google gaining access to your local machine. In that case you are screwed, but employment at Google isn’t actually a factor any more. Moral: Hit Win + L before leaving machine. While we agree with zeel that it’s a pretty safe bet (as long as your computer is not compromised) that your passwords are in fact safe while stored in Chrome, we prefer to encrypt all our logins and passwords in a LastPass vault. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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  • Chrome 32 bêta sort avec un indicateur d'onglets qui jouent un son, une vidéo, utilisent la webcam ou diffusent sur la TV

    Chrome 32 bêta sort avec un indicateur d'onglets qui jouent un son une vidéo, utilisent la webcam ou diffusent sur la TVFidèle à son rythme de sortie des nouvelles versions de Chrome, Google vient de dévoiler la bêta de la version 32 du navigateur pour Windows, Mac et Linux, avec comme nouveauté phare une fonctionnalité permettant d'identifier rapidement les onglets bruyants, ceux qui utilisent la webcam, ainsi que ceux en diffusion sur votre télévision.En gestation depuis fin février sur le canal...

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  • La force du mot de passe serait corrélée au genre d'un individu, d'après une étude, les informaticiens choisiraient des mots de passe forts

    La force du mot de passe serait corrélée au genre d'un individu d'après une récente étudeLe mot de passe est un des éléments essentiels de la sécurité des systèmes d'information. Il constitue très souvent le premier obstacle que doit franchir un hacker pour avoir accès aux informations personnelles d'un utilisateur lambda.Une récente étude vient d'être menée sur quasiment l'ensemble de la population de l'université américaine de Carnegie Mellon. Elle a porté sur l'analyse des mots de passe de 25000...

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