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• Internet Troubles - PPPoE vs PPPoA?

  - by AkkA

  I have been having some internet troubles at home (ADSL2+ connection in Australia). We get random drop-outs from the authentication connection. It will keep the connection to the DSL service, but we lose authentication and either have to restart the router/modem (its combined, a Belkin one, not sure on model number) or unplug the phone cable, wait about 30 seconds and plug it in again. I've called the ISP (Telstra) a few times, but they only offer limited support when we dont use their supported hardware. Apparently something had happened on their side, they checked the box again (at least it sounded that simple), and told me it would be fine. It wasnt. I've replaced all the filters around the house, but that didnt help either. We do live a little bit away from the exchange (get a sync speed of about 3000/900), so I thought it could be due to line noise but that hasnt helped. Telstra allow both PPPoE and PPPoA connections (which I'm configuring through my router, dont have software on the PC side). I've been running PPPoA the whole time, would it make any difference changing it to PPPoE? If not, are there any other theories as to why we would be experiencing these drop-outs? It has been fine for at least 12 months, then suddenly started about 2 months ago.

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• setup lowcost image storage server with 24x SSD array to get high IOPS?

  - by Nenad

  I want to build let's name it a lowcost Ra*san which would host for our social site the images (many millions) we have 5 sizes of every photo with 3 KB, 7 KB, 15 KB, 25 KB and 80 KB per Image. My idea is to build a Server with 24x consumer 240 GB SSD's in Raid 6 which will give me some 5 TB Disk space for the photo storage. To have HA I can add a 2nd one and use drdb. I'm looking to get above 150'000 IOPS (4K Random reads). As we mostly have read access only and rarely delete photos i think to go with consumer MLC SSD. I read many endurance reviews and don't see there a problem as long we don't rewrite the cells. What you think about my idea? - I'm not sure between Raid 6 or Raid 10 (more IOPS, cost SSD). - Is ext4 OK for the filesystem - Would you use 1 or 2 Raid controller, with Extender Backplane If anyone has realized something similar i would be happy to get Real World numbers. UPDATE I have buy 12 (plus some spare) OCZ Talos 480GB SAS SSD Drive's they will be placed in a 12-bay DAS and attached to a PERC H800 (1GB NV Cache, manufactured by LSI with fastpath) Controller, I plan to setup Raid 50 with ext4. If someone is wondering about some benchmarks let me know what you would like to see.

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• Fix bad superblock on logical partition

  - by Chris

  I was following http://www.howtoforge.com/linux_resi...xt3_partitions and when i reboot and run: root@Microknoppix:/home/knoppix# fsck -n /dev/sda7 fsck from util-linux-ng 2.17.2 e2fsck 1.41.12 (17-May-2010) fsck.ext2: Superblock invalid, trying backup blocks... fsck.ext2: Bad magic number in super-block while trying to open /dev/sda7 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 <device> so i ran e2fsck with all the block numbers that you need (forget exactly what tool i used to find where the superblocks are hidden) no dice then i ran testdisk and had it look for the superblock, no results anyone have any ideas? fdisk -l for reference: root@Microknoppix:/home/knoppix# fdisk -l Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x97646c29 Device Boot Start End Blocks Id System /dev/sda1 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 38912 312046593 f W95 Ext'd (LBA) /dev/sda5 64 326 2104320 82 Linux swap / Solaris /dev/sda6 * 327 2938 20972544 83 Linux /dev/sda7 2938 38912 288968672+ 83 Linux To be honest it looks like I lost it... Next step if that happens is to dump the partition to an image file and hope i can find or write some software to parse through the data looking for known file headers, i think.

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• How to calculate unweighted averages in Excel PivotTable?

  - by yonatron

  I often make PivotTables in which each row contains a number of per-person average measures. I then want to look at the unweighted column average for each measure, and usually make some kind of chart from these. Because my individual cells are often averaged from different numbers of data points, the Grand Total row ends up being a weighted average, which I’m not interested in. So I usually make my own average row a few rows above the table to use for my charts. That’s not too much work, but there’s another problem. I often add a few more people’s worth of data to the PivotTables’ source, then refresh the tables. This means my average row needs to be updated to encompass more rows from the PivotTable. Not a huge deal with one table, but when I have lots of them across lots of sheets, I have to do find/replace on a whole bunch of formulas. So: is there a way to automatically get unweighted column averages in a PivotTable, such that when the table is refreshed, the averages don’t change locations and encompass the newly added (or removed) data Thanks

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• MicroSD card getting corrupted for no good reason

  - by ChaosR

  I recently bought an MicroSD card online. It's a Sandisk 16GB class 2. However, it has a nasty problem. Every time I fill it with my data, the fat tables get corrupted. I've tried reformatting it, blanking it, doesn't seem to solve the problem. I have tried windows and linux (ubuntu), both have the problem. I've used my usb microsd readers, and even tried putting it in my phone and putting data on it from there. All have this problem. Now the really odd thing is, besides the corrupted file tables, no programs can find anything wrong with the hardware. I've tried both chkdisk and "badblocks -w", neither give any type of error. Now I don't know if the actual data gets corrupted, or if its just filesystem tables. What happens is that one or more folders start showing a load of chinese-charred (random UTF8 symbols I suppose) folders and files, and it is impossible to do anything with those. All the other data (outside of the corrupted folders) seems fine. I've tried to test it, and the problem doesn't seem to show up until I fill the disk upto about 3~4GB. After that I can still access the data. But as soon as I eject/safely remove/unmount it, the bad things happen somehow. Next time I plug it in, the folders I most recently wrote to (but sometimes also the folders I wrote the time before last time to) are all gibberish. Does anybody have any clue what might be going on here? EDIT: It seems I can't even put ext3 or ext4 on it, they both complain about a corrupted journal. Gheh, guess something is really broken here.

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• How do I uncompress vmlinuz to vmlinux?

  - by Lord Loh.

  I have already tried uncompress, gzip, and all other solutions that come up as google results and these have not worked for me. To get just the image search for the GZ signature - 1f 8b 08 00. > od -A d -t x1 vmlinuz | grep '1f 8b 08 00' 0024576 24 26 27 00 ae 21 16 00 1f 8b 08 00 7f 2f 6b 45 so the image begins at 24576+8 => 24584. Then just copy the image from the point and decompress it - > dd if=vmlinuz bs=1 skip=24584 | zcat > vmlinux 1450414+0 records in 1450414+0 records out 1450414 bytes (1.5 MB) copied, 6.78127 s, 214 kB/s Got these instructions verbatim from a forum online: http://www.codeguru.com/forum/showthread.php?t=415186 This process does not work for me and end up giving errors that states file not found 0024576 and all subsequent numbers. How do I proceed extracting vmlinux from vmlinuz? Thank you. EDITED: This is a reverse engineering question. I have no access to the distro to install any RPM or recompile. I start with nothing but vmlinuz.

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• Desktop PC does not power up on power button

  - by hIpPy

  When I press the power button on my desktop, it does not power up completely. Before I press the power button, I see lights on the motherboard. Everything is normal. On power button press, the fans on the cpu, graphics card and motherboard start to spin a little for a second or two and then they stop. No beeps during this process. It has been doing this for a while now but it used to start up after some trials. Once it starts up, I have NO issues at all like random shutdowns so it is not an issue with OS. Update: I left the desktop off for a few days and it started. I'm just guessing here but it seems as if the PSU (Antec TP2-550ATX) is dying out and does not have enough power now - just a guess. It's an old desktop assembled in 2005 but I have maintained it well. Update: I always keep the desktop running and I never shut it down. During updates or manual restarts, it powers up without issues. I wonder if this sheds lights on the issue. Any idea how I can narrow down the issue? ex: if I can find if the PSU is dying etc. I'd really like to fix the issue. Please help. Thanks. Below is the complete configuration. DFI LAN-Party UT NF4 Ultra-D 6/23 {6.70}, Evercool EC-VC-RE 41/47C, AMD Opteron 170 2.0GHz {1.3.2.16} 1.312V 36/41C, ThermalRight SI-120, Panaflo 120×38mm OCZ Platinum 2×1GB 200MHz 2.66V 3-3-2-7 1T XFX 7800GTX 256MB 475/1250MHz {91.31}, Zalman VF900 Cu led 41/56C WD Caviar 320GB 7200RPM 16MB SATA 3Gb/s Antec TP2-550ATX Antec P180 WinXP sp3 Logitech MX310 Razer Mantis Speed BenQ FP91G+ 19" LCD 8ms DVI Creative Audigy2 ZS {4.42} BenQ DW1640 Logitech z-5300e 5.1 280W Legend: Driver versions: {} User settings: [] Voltage: V Wattage: W Temperature: C (Celsius) min/max

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• Samsung laptop randomly shuts down

  - by Dmatig

  I've rewritten this question because it turned into an indecipherable mess. I have a Samsung R560 laptop that is overheating, and shutting itself down under load consistantly. Thank you quickcel for reccomending me Speedfan to monitor my temps. Here they are (Load / Idle): (Ignore "Temp1 and Temp2", whatever sensors they are they'd always random, pretty sure they're broke). The load temperature is after just 5 minites of playing Fallout 3 - another 5 minutes and it (the GPU - 9600M GS) consistantly breaches the mid 90's then shuts down, so it's hard to get a good picture of it. I'm looking for some solution or way to decrease these temperatures, because they seem far too high even idle. I've tried: Opening up the case and clearing of all dust with compressed air. Updating drivers for my Graphics card Have purchased and am using a notebook cooler I don't want to: Undervolt / underclock (defeats the point of having a more expensive card) Use lower power / performance settings (again, i might as well have bought something cheaper) Is there anything else i can try (software or inexpensive hardware) that can help me fix this? Has anybody had a Samsung laptop and knows if this can be sorted under my warranty, and the turnaround time of sending it off (UK?)(it has always ran hotter than it should, but now at 6 months old is getting hot enough to power off)

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• Cisco IOS BVI ACL: Only allow established UDP

  - by George Bailey

  Related: Cisco IOS ACL: Don't permit incoming connections just because they are from port 80 I know we can use the established keyword for TCP.. but what can we do for UDP (short of replacing a Bridge or BVI with a NAT)? Answer I found out what "UDP has no connection" means. DNS uses UDP for example.. named (DNS server) is lisenting on port 53 nslookup (DNS client) starts listening on some random port and sends a packet to port 53 of the server and notes the source port in that packet. nslookup will retry 3 times if necessary. Also the packets are so small that it does not have to worry about them coming in the wrong order. If nslookup receives a response on that port that comes from the servers IP and port then it stops listening. If the server tried to send two responses (for example a response and a response to the retry) then the server would not care if either of them made it because the client has the job to retry. In fact.. unless ICMP 3/3 packet gets through the server would not know about a failure. This is different from TCP where you get connection closed or timed out errors. DNS allows for an easy retry from the client as well as small packets.. so UDP is an excellent choice because it is more efficient. In UDP you would see nslookup sends request named sends answer In TCP you would see nslookup's machine sends SYN named's machine sends SYN-ACK nslookup's machine sends ACK and the request named's machine sends the response That is much more than is necessary for a tiny DNS packet

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• Dell PS/2 Keyboard Stops Working Randomly After Power Disturbance

  - by Kenneth Murphy

  I have a Dell PS/2 keyboard connected to a desktop PC running Slackware 12.2 & Windows XP. After a recent, brief power outage/disturbance at my home, the keyboard has begun to quit working at random times. It has stopped at POST, but not by keyboard error -- I have to press the F1 key to continue booting, and at times the keyboard has already stopped working. Other times, the keyboard will work perfectly for a long time (a day or more) before it finally quits. It has stopped at boot, in Windows XP, and in Slackware. The led lights continue to work regardless. I have tried another PS/2 keyboard and it seems to be immune to this problem. The USB mouse always works. Does anyone have any ideas about how this might have happened? If this is related to the power disturbance that killed the power to the running PC, is it feasible that it would have only fried the keyboard itself (which still works sometimes) and not the PS/2 port nor anything else? I have experienced no other problems since the event.

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• GNU Screen and Finch Not Playing Nicely

  - by Sean M

  I use finch for instant messaging, and for persistence, finch is one of the things that runs in my screen session. There are three main computers that I access my screen session from, and each works at a different screen resolution. Because of the different resolutions, when I switch computers, I use screen -rd to attach to my screen session. Using screen -x results in problems. When I attach to the session, though, finch experiences display problems. I have to wait up to several minutes for finch to become responsive - it doesn't redraw properly at all. Trying to switch between chats just writes ^n and ^p, or ^(1-9) for numbers. It fixes itself after some time. Using ctrl-l does not help. Switching back and forth between screen windows does not help. This is an annoying behavior that I don't experience with any other applications running in screen. Is this a bug in screen or finch, and if not, what can I change about my configuration to correct it ? (would appreciate it if "finch" could be used as a tag for this instead of or in addition to "pidgin")

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• What does "incoming" and "outgoing" traffic mean?

  - by mgibsonbr

  I've seen many resources explaining how to set up a server's firewall to allow incoming and outgoing traffic on HTTP standard ports (80 and 443), but I can't figure out why I would need either of them. Do I need to unblock both for a "regular" web site to work? For file uploads to work? Are there situations where it would be advisable to unblock one and leave the other blocked? Sorry if that's a basic question, but I couldn't find it explained anywhere (also I'm not a native english speaker). I know in a "regular" web site the client is always the one who initiates a request, so I'm assuming a web server must accept incoming traffic on those ports, and my common sense tells me the server is allowed to send a response without unblocking anything else (otherwise it wouldn't make sense to have two types of rules). Is that correct? But what is an outgoing web (service) traffic, and what would be its use? AFAIK if the server wanted to initiate a connection with another machine, the specific port that matters is the one in the other end (i.e. the destination port would be 80), on its end any free port could be used (the source port would be random). I can open HTTP requests from my server (using wget for instance) without unblocking anything. So I'm assuming my concepts of "incoming" and "outgoing" are wrong somehow.

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• To what extent is size a factor in SSD performance?

  - by artif

  To what extent is the size of an SSD a factor in its performance? In my mind, correct me if I'm wrong, a bigger SSD should be, everything else being equal, faster than a smaller one. A bigger SSD would have more erase blocks and thus more leeway for the FTL (flash translation layer) to do garbage collection optimization. Also there would be more time before TRIM became necessary. I see on Wikipedia that it remarks that "The performance of the SSD can scale with the number of parallel NAND flash chips used in the device" so it seems throughput also increases significantly. Also many SSDs contain internal caches of some sort and presumably those caches are larger for correspondingly large SSDs. But supposing this effect exists, I would like a quantitative analysis. Does throughput increase linearly? How much is garbage collection impacted, if at all? Does latency stay the same? And so on. Would the performance of a 8 GB SSD be significantly different from, for example, an 80 GB SSD assuming both used high quality chips, controllers, etc? Are there any resources (webpages, research papers, presentations, books, etc) that discuss correlations between SSD performance (4 KB random write speed, latency, maximum sequential throughput, etc) and size? I realize this does not really sound like a programming question but it is relevant for what I'm working on (using flash for caching hard drive data) which does involve programming. If there is a better place to ask this question, eg a more hardware oriented site, what would that be? Something like the equivalent of stack overflow (or perhaps a forum) for in-depth questions on hardware interfaces, internals, etc would be appreciated.

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• Applications randomly alt-tab? (especially full screen games)

  - by Henry Scotts

  I'm not sure when this began, how it happens, or why it happens, but it is quite bothersome and apparently random. Just randomly throughout the day my computer will just go to the desktop. I could be in a full screen game and it will just immediately alt tab and present the desktop. Or I could be watching a movie and this happens. Sometimes it happens once every three hours and other times (just today actually) it did it twice in the span of 30 seconds. I am positive I am not pressing a hotkey because I launched a game, sat idle, and noticed it alt tab while cleaning up around my room after about 20 minutes. Sometimes it goes days without this happening. Specs: Windows 7 Ultimate 64 Bit, 10 gigs of RAM, GeForce GTX 260, Intel Xeon CPU. I also have basically nothing running when it happens other than the game and FireFox. My FireFox add-ons: Adblock Plus, Download Statusbar, Firebug, FirePHP, lazarus form recovery, tree-style-tabs, yslow. I doubt FireFox is causing the issue but I figured I'd include it anyway because it is the only application I have running when it happens. As for user processes I have running: VCDDaemon (context menu for virtual clone drive), razerhid (mouse), OSD, taskhost, dmw (desktop window manager), anyfullscreengame, audiorepeater, netsession_win, explorer, razerofa, tsvncache, firefox, plugin-container, and EKIJ5000MUI (printer). Whew. Okay. That was a lot of information. If someone could diagnose this I would be most grateful for this has been around with me for years.. Thanks for reading! PS: I doubt it's a virus because I never download illegal software and pretty much only browse Reddit and Stackexchange and play games. If it was a virus it would be a pretty lame one.. Hah..

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• Netgear router keeps disconnecting iPhone

  - by DisgruntledGoat

  My old router (Voyager 2091) packed up so I just got a new router - a Netgear N150 model DGN1000. My laptop connects OK wirelessly, but my iPhone 4S is constantly getting "disconnected" - it has perfect wifi signal and is seemingly connected to the router, but no pages load (it says "server cannot be found"). If I disconnect manually ("forget this network") then reconnect, it works fine again for a random amount of time (usually 10-30 minutes) then I get the same problem again. I've done some searching and this appears to be a known problem - there are dozens of forum posts out there lamenting similar connection problems. The only advice I have seen is to set a specific channel under Wireless Settings on the router CP, although every forum post recommends a different channel! 1, 3, 5, 6, 11... I have tried them all for hours at a time and get the exact same problem. The firmware is up to date. Is there an actual solution for this, or do I need to get a different router just to be able to use my iPhone?

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• Importing long numerical identifiers into Excel

  - by Niels Basjes

  I have some data in a database that uses ids that have the form of 16 digit numbers. In some situations i need to export the data in such a way that it can be manipulated in excel. So i export the data into a file and import it into excel. I've tried several file formats and I'm stuck. The problem I'm facing is that when reading a file into excel that has a cell that looks like a number then excel treats it as a number. The catch is that (as far as i can tell) all numerical values in excel are double precision floating point which have a precision of less than 16 digits. So my ids are changed: very often the last digit its changed to a 0. So far I've only been able to convince excel to keep the Id unchanged by breaking it myself: by adding a letter or symbol to the Id. This however means that in order to use the value again it must be "unbroken". Is there a way to create a file where i can specify that excel must treat the value as a text without changing the value? Or its there a way to let excel treat the value as a long (64bit integer)?

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• Hard Disk Not Counting Reallocated Sectors

  - by MetaNova

  I have a drive that is reporting that the current pending sectors is "45". I have used badblocks to identify the sectors and I have been trying to write zeros to them with dd. From what I understand, when I attempt writing data directly to the bad sectors, it should trigger a reallocation, reducing current pending sectors by one and increasing the reallocated sector count. However, on this disk both Reallocated_Sector_Ct and Reallocated_Event_Count raw values are 0, and dd fails with I/O errors when I attempt to write zeros to the bad sectors. dd works fine, however, when I write to a good sector. # dd if=/dev/zero of=/dev/sdb bs=512 count=1 seek=217152 dd: error writing ‘/dev/sdb’: Input/output error Does this mean that my drive, in some way, has no spare sectors to be used for reallocation? Is my drive just in general a terrible person? (The drive isn't actually mine, I'm helping a friend out. They might have just gotten a cheap drive or something.) In case it is relevant, here is the output of smartctl -i : Model Family: Western Digital Caviar Green (AF) Device Model: WDC WD15EARS-00Z5B1 Serial Number: WD-WMAVU3027748 LU WWN Device Id: 5 0014ee 25998d213 Firmware Version: 80.00A80 User Capacity: 1,500,301,910,016 bytes [1.50 TB] Sector Size: 512 bytes logical/physical Device is: In smartctl database [for details use: -P show] ATA Version is: ATA8-ACS (minor revision not indicated) SATA Version is: SATA 2.6, 3.0 Gb/s Local Time is: Fri Oct 18 17:47:29 2013 CDT SMART support is: Available - device has SMART capability. SMART support is: Enabled UPDATE: I have run shred on the disk, which has caused Current_Pending_Sector to go to zero. However, Reallocated_Sector_Ct and Reallocated_Event_Count are still zero, and dd is now able to write data to the sectors it was previously unable to. This leads me with several other questions: Why aren't the reallocations being recored by the disk? I'm assuming the reallocation took place as I can now write data directly to the sector and couldn't before. Why did shred cause reallocation and not dd? Does the fact that shred writes random data instead of just zeros make a difference?

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• Nginx proxy to IIS Connection Timeout

  - by MitMaro

  I am having an issue with random timeouts with a Nginx proxy connecting to an IIS machine. I have been watching a packet capture between the two servers and it seems that the IIS machine is receiving a SYN packet but is not responding with what I think should be an ACK response. Before the timeout occurs there seems to be a slower response from the IIS server. There is no unusual memory or processor usage on the IIS or Nginx machine. Some information on the servers and setup: Nginx Machine: Ubuntu 10.04 64bit Nginx 0.7.65 Amazon EC2 Windows Machine: Windows Server 2008 IIS 7 ASP.net Application in Integrated Mode Nginx Error: 2011/01/10 17:57:40 [error] 8297#0: *30 connect() failed (110: Connection timed out) while connecting to upstream, client: 209.***.***.***, server: secure.example.com, request: "GET /a/path/deliver.aspx HTTP/1.1", upstream: "http://***.***.***.****:****//another/path/deliver.aspx", host: "secure.example.com" WireShark Packets 6521.449528 10.***.***.*** -> 174.***.***.*** TCP 38695 > us-cli [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=477422103 TSER=0 WS=7 6524.443239 10.***.***.*** -> 174.***.***.*** TCP 38695 > us-cli [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=477422403 TSER=0 WS=7 6530.443241 10.***.***.*** -> 174.***.***.*** TCP 38695 > us-cli [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=477423003 TSER=0 WS=7

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• How does VirtualBox's memory usage work?

  - by DrFredEdison

  I've been running several VM's with VirtualBox, and the memory usage reported from various perspectives, and I'm having trouble figuring how much memory my VMs actually use. Here is an example: I have a VM running Windows 7 (as the Guest OS) on my windows XP Host machine. The Host Machine Has 3 GB of RAM The Guest VM is setup to have a base memory of 1 GB If I run Task Manger on the Guest OS, I see memory usage of 430 MB If I run Task Manger on the host OS, I see 3 processes that seem to belong to VirtualBox: VirtualBox.exe (1), using 60 MB of memory (This one seems to have the most CPU usage) VirtualBox.exe (2), using 20 MB of memory VBoxSvc.exe, using 11.5 MB of memory While running the VM, the Host OS's memory usage is about 2 GB When I shut down the VM, the Host OS's it goes back to memory usage goes down to about 900 MB So clearly, there are some huge differences here. I really don't understand how the GuestOS can use 400+ MB, while the Host OS only shows about 75 MB allocated to the VM. Are there other processes used by VirtualBox that aren't as obviously named? Also, I'd like to know if I run a machine with 1 GB, is that going to take 1 GB away from my host OS, or only the amount of memory the Guest machine is currently using? update Somene expressed distrust over my memory usage numbers, and I'm not sure if that distrust was directed at me, or my Host OS's Task Manager's reporting (which is perhaps the culprit), but for any skeptics, here is a screenshot of those processes on the host machine:

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• Need help trying to diagnose Symmetrix SAN performance issues

  - by arcain

  I am helping to benchmark hardware for a new SQL Server instance, and the volume presented to the OS for the data files is carved from a set of spindles on a Symmetrix SAN. The server has yet to have SQL Server installed, so the only activity on the box is our benchmarking. Now, our storage engineers say that this volume and it's resources are dedicated to our new server (I don't have access to see the actual SAN config) however the performance benchmarks are troubling. For example, the numbers look good until suddenly, and randomly, we see in our IO benchmarking tool wait times of 100 seconds, and disk queue lengths of 255 in perfmon. This SAN has an 8 GB cache, plus there are other applications besides ours that use the SAN. I'm wondering if (even though the spindles for our volumes should be dedicated to us) the cache may be getting hammered during the performance testing, or perhaps the spindles our volumes are on aren't really dedicated to us. We're not getting much traction from our storage engineers in helping us track down the problem, so if anybody has experience with diagnosing a problem like this and would like to share insights and troubleshooting methodologies, I'd appreciate it.

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• Drupal 7: One-time user account

  - by Noob

  I'm going to create a survey in Drupal 7 with the webform module, installed on a debian system which may be adapted in every way. The users (personally known, approx. 120) doing that survey will walk into a room and complete the survey in browsers on different computers. After that, they'll leave the room and other persons will enter, complete the survey on the same computers and so on. Each user may enter only one submission. The process needs to be anonymous, i. e. I mustn't have any idea of who did wich submission. My current solution is to generate random one-time-passwords and hand out one password per user (without noting who got which password). Within the survey there will be a password field where the one-time-password is entered. The value is checked by webform to be unique. I'll get the data via csv or Excel and verify the passwords manually in excel by comparing them to the list of valid passwords. The problem is: I don't like the idea of manually generating the password list, copying it to excel and doing a manual check. That's a good idea for one-time-use, but we're going to repeat the survey every once in a while. I'd rather generate one-time-logins (like user0001/fdlkjewf, user0002/dfrefnnr, ...) for each survey, hand them out to the users and let drupal/debian/whatever check whether a submission is valid or not. Do you have any idea how to batch-generate about 120 users with one-time-passwords in Drupal 7 and verify that each user may submit the form only once? Do you even have a better idea how to accomplish the task within the intranet? Thank you for your help.

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• How browsers handle multiple IPs

  - by Sandman4

  Can someone direct me to information on exact browsers behavior when browser gets multiple A records for a given hostname (say ip1 and ip2), and one of them is not accessible. I interested in EXACT details, like (but not limited to): Will browser get 2 IPs from OS, or it will get only one ? Which ip will browser try first (random or always the first one) ? Now, let's say browser started with the failed ip1 For how long will browser try ip1 ? If user hits "stop" while it waits for ip1, and then clicks refresh which IP will browser try ? What will happen when it times-out - will it start trying ip2 or give error ? (And if error, which ip will browser try when user clicks refresh). When user clicks refresh, will any browser attempt new DNS lookup ? Now let's assume browser tried working ip2 first. For the next page request, will browser still use ip2, or it may randomly switch ips ? For how long browsers keep IPs in their cache ? When browsers sends a new DNS request, and get SAME ips, will it CONTINUE to use the same known-to-be-working IP, or the process starts from scratch and it may try any of the two ? Of course it all may be browser dependent, and may also vary between versions and platforms, I'd be happy to have maximum of details. The purpose of this - I'm trying to understand what exactly users will experience when round-robin DNS based used and one of the hosts fails. Please, I'm NOT asking about how bad DNS load balancing is, and please refrain from answering "don't do it", "it's a bad idea", "you need heartbeat/proxy/BGP/whatever" and so on.

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• Router not connecting to the internet

  - by Peter

  I had a weird problem this morning with my router - it's an Alice Gate VoIP 2 Plus WI-FI - not connecting to the internet after more or less 1 hour online (I'm always connected with the ethernet cable). The led status lights for Power, WI-FI, ADSL, Internet, Service should be on in order to be connected and navigate online. The problem was that the leds ADSL, Internet were off and I did not know why because it never happened before. I looked at the stats in the settings and the numbers for Bytes/Packages for both Sent/Received were there and increasing but I couldn't connect to the internet. I called tech support, they checked and told me to keep the router on for 48 hours because they were checking it. I've reset it twice before and after I called tech support and it still did not work so after about 2 hours of waiting I tried connecting using WI-FI and the leds 'magically' turned on, first the ADSL and Internet(Internet led always turns on last). At this point I'm curious what could of caused this and I'm doubting that the tech-support guys did something. What could of been the problem with the ethernet cable not connecting in the first place? It always works. What do the tech support guys normally do when they tell me to keep the router on so they can 'check it'? PS: I'm using ubuntu 32 bit

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• How can I proxy multiple LDAP servers, and still have grouping of users on the proxy?

  - by Chris

  I have 2 problems that I'm hoping to find a common solution to. First, I need to find a way to have multiple LDAP servers (Windows AD's across multiple domains) feed into a single source for authentication. This is also needed to get applications that can't natively talk to more than one LDAP server to work. I've read this can be done with Open LDAP. Are there other solutions? Second, I need to be able to add those users to groups without being able to make any changes to the LDAP servers I'm proxying. Lastly, this all needs to work on Windows Server 2003/2008. I work for a very large organization, and to create multiple groups and have large numbers of users added to, moved between, and removed from them is no small task. This normally requires tons of paperwork and a lot of time. Time is the one thing we don't normally have; dodging the paperwork is just a plus. I have very limited experience in all this, so I'm not even sure what I'm asking will make sense. Atlassian Crowd comes close to what we need, but falls short of having it's own LDAP front end. Can anyone provide any advice or product names? Thanks for any help you can provide.

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• Router reporting failed admin login attempts from home server

  - by jeffora

  I recently noticed in the logs of my home router that it relatively regularly lists the following entry: [admin login failure] from source 192.168.0.160, Monday, June 20,2011 18:13:25 192.168.0.160 is the internal address of my home server, running Windows Home Server 2011. Is there anyway I can find out what specifically is trying to login to the router? Or is there some explanation for this behaviour? (not sure if this belongs here or on superuser...) [Update] I've run both Wireshark and netmon for a while on my home server. Wireshark captured the traffic, but didn't really show anything useful (or nothing I could make use of). A simple HTTP GET request is sent from the server (192.168.0.160) to the router (192.168.0.1), from a seemingly random port (I've seen examples from 50068, 52883), and it appears to do it twice in quick succession (incrementing port by 1), about every hour. Running netstat around the time of the failure didn't show anything (probably too long after anyway). I tried using netmon as it categorises by process, so I thought it might show a corresponding process for the port. Unfortunately, this comes in under the 'unknown' category, meaning it's basically just a slower, less useful Wireshark. I know there's not much to go on here, but does this help in anyway?

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