Discuss March 2007

discuss@lists.centos.org

337 participants
401 discussions

differnt results between df and ls
by Tom Brown 29 Mar '07

29 Mar '07

Hi this is more than likely a general linux question but on a CentOS4 box whats going on here? # ls -al foo.txt -r--r--r-- 1 xxx xxx 1373149856 Mar 28 04:34 foo.txt # du -sh foo.txt 808M foo.txt any ideas ?

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DDR2 compile times (was Re: segfaults with 8 gig of ram)
by tblader 29 Mar '07

29 Mar '07

Hello All. Below are some compile times for 2.6.20 on an fx-62 running Centos64 with various 2 gig sticks of dual channel ram (See previous posts with subject of 'segfaults with 8gig of ram' for more details.) It seems dual channel will compile a kernel faster, but only gained around 30 seconds over 20 minutes. Below are the shortest/longest compile times of several compiles done over the weekend. Compile consisted of make menuconfig (save .config) time make dep clean bzImage modules 2 sticks dual channel @800mhz 10 samples ================================ real 791.46 user 664.10 sys 93.85 real 799.88 user 665.30 sys 93.87 4 sticks dual channel @400mhz 5 samples (before it hurled booting) ================================ real 876.19 user 712.98 sys 116.18 real 846.06 user 710.16 sys 115.42 3 sticks single channel @800mhz 6 samples ================================ real 815.74 user 673.73 sys 108.30 real 822.95 user 674.32 sys 108.62 -- Flambeau Inc. Technology Center - Baraboo, WI Email : tblader(a)flambeau.com Keyserver: http://pgp.mit.edu KeyID: 0x00E9EC2C

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RE: [CentOS] Tape drive recommendations
by Mark Schoonover 29 Mar '07

29 Mar '07

Joshua Baker-LePain wrote: > On Wed, 28 Mar 2007 at 11:54pm, Mark Schoonover wrote > > I really didn't mean for this to turn into a tape vs. disk based > backups debate -- everyone has their own needs and ways of meeting > them. But I have to disagree with the following: > >> Tape backups require user intervention everyday. There's no way >> around it, especially if you're testing your backups for reliability. > > No, they don't. With a library, you only need to change tapes when > you're out of slots (if then, depending on your library, dataset > size, retention needs, etc). And any decent backup software should > have some sort of verification built in or easily scripted. If you rely solely on your tape software verification to tell you your tapes are 100%, there will come a day, you'll be in for a surprise. The only 100% sure fire way to determine if your tapes are good is to actually restore from them back to a drive, and open them with the applications that created those files. Only after that kind of testing, can you be sure your tapes are good. I've had many tapes verified from the days of Arcserve, through Brightstor, Arkeia, CTAR and BRU. All of these backup software systems ran, and verified flawlessly, then a disaster struck only to find out my verified tapes actually had problems with them. Now, the $64K is, how many files do you need to test?? :) Thanks! Mark Schoonover *** Winner of the 2008 Best Psychic Award IS Manager American Geotechnical - California, Nevada and Arizona V-> 858.450.4040 F-> 714.685.3909 C-> 858.472.3816

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segfaults with 8 gig of ram
by tblader 29 Mar '07

29 Mar '07

Hello All. I have five Centos 4.4 x86_64 (amd fx-62) boxes with 4 gig of Corsair dual channel ram running kernel 2.6.9-42.0.10.EL (smp). The sixth box is the same except for video card and ram. It is using 8gig of GSkill dual channel ram and has a very cheap ATI video card in it. This box will segfault on boot unless I use noapic acpi=off and nolapic. Even with these boot params, the box is not 100% stable. I have seen udev segfault right when booting and also when copying 15 meg files from /tmp to /usr will lock things up sometimes. Yum and Perl have gotten corrupted as well at different times. I have 5 fans in the box to vent heat and the BIOS reports the CPU running around 90 degrees Farenheit when rebooting. I have run memtest86 (from Knoppix 5.1) all night long on the 8 gig of ram and it comes up OK. In the past, we have found problematic Corsair ram this way. This 8 gig seems to be OK as far as memtest thinks. Today I will begin removing ram and testing to see what happens. Does anyone have some ideas what might be the problem? All the other five boxes with Corsair ram work fine. Thanks

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Cups issue - keeps re-writing cupsd.conf and mime.types
by Justin Barth 29 Mar '07

29 Mar '07

Hi, My Centos 4.4 server at home is serving a Samsung SCX-4521F printer, which the *nix and Win clients connect to through ipp. Every so often (maybe once a month), the cupsd.conf and mime.types files are updated, which makes the printer unavailable to the clients. My fix so far has been to stop cups, overwrite the files with cupsd.conf.working and mime.types.working (these are backup files of the originial working files), then start cups. Now my question is - how simple would it be to make a bash script that will monitor if the files have been updated, then perform the above actions automatically? Or, how would I stop the files from being updated in the first place? I seem to remember coming across an article about cups-config-daemon, which can update the files occasionally - I have disabled cups-config-daemon in chkconfig, but somehow these 2 files are still being updated. Thanks for any advice! -justin

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RE: [CentOS] Tape drive recommendations
by Mark Schoonover 29 Mar '07

29 Mar '07

Les Mikesell wrote: > Mark Schoonover wrote: >> Les Mikesell wrote: >>> Mark Schoonover wrote: >>>> John R Pierce wrote: >>>>> Aron.Darling(a)Emulex.Com wrote: >>>>>> Loader are totally a love/hate relationship. They do make life a >>>>>> lot easier as they do the tape movements for you which can be a >>>>>> tedious thing at times. With a loader or library you can script >>>>>> the entire operation with tar, MTX and MT and let cron do all the >>>>>> work for you. Always look for the OEM rather than buying the name >>>>>> brand equipment, they are most always the same HW and FW with a >>>>>> different model number in it. >>>>> otoh, its hard to beat a 3 year warranty and on location support >>>>> from the same vendor as your server hardware, assuming your a >>>>> brand name shop in the first place.... hugely reduces finger >>>>> pointing when there's a complex issue to resolve. with OEM >>>>> hardware bought on the whitebox market, you're often faced with >>>>> replace or self-repair option at cost. >>>>> >>>> Having used a 20 tape library, and suffering through restores with >>>> AIT2 tapes taking 10-12 hours per tape, I gave up on them. I went >>>> with good old rsync, and built up a 4 TB system to handle backups. >>>> Once configured, it's nearly a 100% hands off solution. You can >>>> read about what I've done here: >>>> http://marks-tech-pages.blogspot.com Works great especially for >>>> TBs of data that needs to be backed up every day. >>> If you want something that stores the backups much more efficiently >>> (with a price in processing to do it), look at backuppc: >>> http://backuppc.sourceforge.net/ >>> >>> It compresses everything and hardlinks all duplicates so you can >>> keep about 10x what you'd expect online, and it has a nice web >>> interface for browsing the backups and doing restores. >> >> Thanks Lee. I did look at backuppc before, and I didn't want >> anything that compresses files, or used a web interface. Using >> rsync, it's a matter of scp to restore, and that's it. I do use >> hardlinks to duplicate data, so my storage requirements are kept as >> small as possible. Just about any CentOS system can be configured to >> run backups in the manner I've written up, nothing extra to install >> or learn. So, like most things, it boils down to individual needs >> and expertise. I know for myself, tape backups just weren't working >> well at all. >> > > Backuppc can be configured to not compress, although I think the > filenames are still somewhat mangled and don't have their real > attributes so you can't access them directly. The web interface is > also optional and there are command line tools for everything you > need. It is handy to be able to download a single file or tar/zip > archive directly through a browser, though - and in the latest > version you can edit the configuration through the web interface. I've thought about adding a web restore so users can restore their own files to their own home directories. Most of my problems come from my graphics dept, where it's not uncommon for them to 'accidently' delete 500GB of data. It would be nice to offload those kinds of requests to the users, but only to a point, and on an employee by employee basis. Mark

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RE: [CentOS] Tape drive recommendations
by Mark Schoonover 29 Mar '07

29 Mar '07

John R Pierce wrote: > Mark Schoonover wrote: >> Cost is another factor. An Exabyte LTO3 1x7 loader is MSRP $6500, >> with 20 tapes $1130 in a pack. My 4TB backup server cost just under >> $5000 at the time, cheaper today. Then, you have the daily admin of >> flipping tapes. Disks run without intervention once configured, and >> it's nice to have especially if you have employees working over the >> weekends, or on holidays. >> > > > HP's version of that same LTO3 1/8 autoloader is around $5000 street > price (sometimes under $4500). The Quantum OEM version > ("Superloader") is about the same. > > of course, 20 LTO3 tapes is 16 terabytes. and you can have another > 16 terabytes in archive for another $1100 or whatever. That 1/8 > autoloader holds 8 of them, which is 6.4 terabytes online with no > operator intervention required until it comes time to ship a box of > tapes to the offsite vault. > Assuming 2:1 compression will you get 16TB, but with my data, 1.3:1 is more realistic. Now that you mention it, a similar disk backup system is located 100 miles away in a colo site. Every night I do offsite backups, automatically. No shipping tapes, or other user intervention. Tape backups require user intervention everyday. There's no way around it, especially if you're testing your backups for reliability. Mark

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Complex sendmail alias handling
by Steve Campbell 29 Mar '07

29 Mar '07

Getting in late on this one, but if I didn't need to spend money, couldn't spend money, or what ever the reason may be, and the aliasing was something that needed changing on a schedule, then why not just set up multiple alias files, run cron to replace them when needed, and "newaliases", all in cron scripts? You would need to maintain as many versions as required, but sounds like it might work with minimal effort and expense. Complex is a relative term, and this may be oversimplifying, but it would work. Steve Campbell campbell(a)cnpapers.com Charleston Newspapers

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NPTL degraded?
by Lonny Selinger 29 Mar '07

29 Mar '07

I'm not sure what has happened but for some reason my CentOS 4 system is showing me using default threads?? # getconf GNU_LIBPTHREAD_VERSION linuxthreads-0.10 # uname -rimpv 2.6.9-42.0.10.EL #1 Tue Feb 27 09:24:42 EST 2007 i686 athlon i386 I could have sworn it used to show: NPTL 2.3.4 Like a couple other machines. Any ideas what might have changed this or how I get it back??? the devel package for NPTL is installed but from my understanding that has little to do with why getconf is showing this. I'm feeling new here :-) TIA -- Lonny -- "To mess up a Linux box, you need to work at it; to mess up your Windows box, you just need to work ON it."

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pagecache corruption on Tyan S3870
by Dan Halbert 28 Mar '07

28 Mar '07

A couple of months ago I reported some problems with a batch of Tyan K8SSA (S3870) based machines. We are continuing to have an odd problem with these boxes, and if anyone has seen something similar elsewhere, I'd appreciate hearing about it. These boxes are running Centos 4.4 x86_64 with kernel 2.6.9-42.0.3.ELsmp. They are dual Opteron 265's (dual core) with 4x2GB DIMM's. The DIMMs used to be mixed sizes, but Tyan recommended making them all the same, and the vendor made the substitutions. We have also clocked the memory down from 400 MHz to 266 MHz, also on the advice of Tyan. The symptom is that some large (700MB to >1GB) files opened for read and then closed show corruption in the pagecache. One or more 4k blocks in a file will be completely trashed. It's as if a random page of other data is substituted. A reboot or a flush of the pagecache fixes the problem, so it's only in the pagecache, not on disk. We are doing regular MD5 checksums of the files, which shows up the problem, in addition to having our application crash from time to time. We have some older Tyan motherboards that don't show this problem. At this point it seems it is either a hardware problem or a kernel motherboard-support problem, but it's pretty baffling. Thanks, Dan

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Discuss March 2007