Discuss October 2005

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266 participants
334 discussions

/proc process information on centos 4.1
by Jerry Geis 04 Oct '05

04 Oct '05

Is there a way to tell through /proc or something else which files a process has open and more importantly what position the read pointer is in for that open file? As an example if I am reading a file with a program I have no control over, and I kill that program, I need to know when in the data file that program was reading at that time. Is this information available and if so how to read it? Thanks, Jerry

3 2

Cron script crashing server...
by Ian mu 04 Oct '05

04 Oct '05

Hiya, have a bit of an odd problem so looking for thoughts before proceeding any more. Problem is on centos3 (also runs fine on another but fails on another, so not sure this is an issue or not), dual xeon setup. Basically I have a perl script that runs once, first thing every morning, gathering some stats (currently turned off due to problem). Crontab -l shows the following... 00 6 * * * nice /home/statsman/stats/run_stats.sh >/dev/null 2>&1 (.sh file basically sources with full path a config with some vars, then runs the perl script). There are a couple of other scripts in the crontab which run absolutely fine, so cron itself seems to be working, its just the combination. If I run this (at that time or anytime) via cron, the whole server totally dies no warning, nothing in logs instantly. If I watch in top waiting for the cron you don't even see it appear, machine just totally hangs, can't ping or anything, needs a cold boot. Nothing in logs or anything apart from bootup info after. If I run the perl script outside of cron from any folder at all, it works fine, never crashes which is where I'm confused, its only as soon as its run from cron. To test I've put it on a test machine, and to confuse it further runs absolutely fine under cron (old redhat install though) no matter what I do, it also seems to run fine on other machines (except one with identical problem) and runs fine from cron on other linux dists/machines, but can't do as much testing on them. I'm really not sure where the problem lies, so may be offtopic, I'm just confused why it runs on some and not others (although maybe running the same version, its possible they were configured slightly different on install), and pretty much clutching at straws. Worse thing is machines a production one, and want to keep downtime to a minimum, so trying to get some angle on what may be wrong before testing more. Any thoughts much appreciated. Ian

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Centos 4.1 on RaQ 550?
by Paul R. Ganci 04 Oct '05

04 Oct '05

Has anyone ever tried to install 4.0 or 4.1 on an old Sun RaQ 550 Cobalt machine? If so would you be willing to share your procedure and experience? I have spent several hours googling and have found how to do this with Fedora Core 1 using a 2.4 kernel. However I am wondering what Cobalt specific patches have to be applied to get 2.6 kernel to work. I have not found anything related to building a functional 2.6 kernel for the RaQ 550. Otherwise, I am assuming that the install procedure would be very similar for Centos 4.1 and Fedora Core 1. -- Paul (ganci(a)nurdog.com)

3 3

CentOS 4.1 iSCSI support
by Morten 03 Oct '05

03 Oct '05

Hi. I found this cached in google: "The initial release of CentOS 4 does not include iSCSI software initiator or target support. Support for iSCSI is being evaluated for addition in a future update to CentOS 4." What is the status on iSCSI for CentOS 4.1? I've tried to install it using yum but cannot seem to get the appropriate package names.. And the above note suggests that they may not even be available. How do I get iSCSI support on 4.1? Can I use the 3.1 package or? Many thanks. Morten

3 5

FreeNX and bash-completion
by Maciej Żenczykowski 03 Oct '05

03 Oct '05

Hi! I have the following packages installed: freenx-0.4.4-1.centos4.noarch from extras bash-completion-20050721-1.2.el4.rf.noarch from dries/dag bash-3.0-19.2.i386 from base seems to result in a non-working nxserver (the window manager doesn't start up, although X applications can be launched via logging in through a seperate ssh and setting the DISPLAY variable accordingly)... As far as I can tell: nxserver calls nxnode which sources ~/.bash_profile which sources ~/.bashrc which sources /etc/bashrc which sources /etc/profile.d/*.sh including /etc/profile.d/bash_completion.sh which sources /etc/bash_completion - which doesn't return (or rather somehow quits, thus causing the skipping of the execution of the X window manager). Anyway the point is that the line after sourcing ~/.bash_profile in nxnode does not get called (when the /etc/bash_completion file is present). Not sure if the problem is in nxserver or in bash_completion, but renaming the /etc/bash_completion file fixes the problem... Anyone feel like debugging more of this? (the bash_completion file is rather magicky and I don't feel inclined to dig in it...) Cheers, MaZe.

3 4

memory leak in Centos 4.1 and 4.0
by Peter Farrow 03 Oct '05

03 Oct '05

Centos 4.0 and 4.1 seem to have a memory leak somewhere and I can't find out what is doing it. I think it may be dovecot. I have installed hundreds of Linux machines, centos/redhat/suse in the past as firewalls and mail relays and use the same/similar methodolgy and config for each. I have found that since Centos 4.0 and 4.1 came along machines that have run well for years and months, suddenly and systematically start running out of memory after a few weeks/months of uptime. The symtpom is the load average goes up and up as the machine creeps into swap usage and eventually the machine has to be rebooted.... this only happened with the introduction of Centos 4 and of course that means Dovecot for the IMAP server.... hmmmm...... Anyone else seen this, P.

6 14

OS does not see all my RAM
by Robin Mordasiewicz 03 Oct '05

03 Oct '05

My BIOS shows all my RAM, but when I boot up linux it does not see all the RAM I have two one GIG sticks of RAM, which show up in my bios, but when typing free, I see that it only shows 256Megs. Is there a way to specify the amount of RAM if linux cannot detect this, or how can I fix/tweak the OS to recognize the amount of RAM my OS is centos-4-x86_64 on a DELL 1850 [root@smtcorav02 ~ ]# free total used free shared buffers cached Mem: 251360 220136 31224 0 3932 64748 -/+ buffers/cache: 151456 99904 Swap: 524280 0 524280 --

6 6

Symantec ghost and CentOS 3.4/4.0
by Drew Weaver 03 Oct '05

03 Oct '05

Anyone have any experience getting ghost to do a successful image with CentOS, Fedora, or RHEL? It worked great with RH9, but now a days I find it nearly impossible to get it to work properly. Any tips would be helpful. We spin up a large number of servers on a weekly basis and it would be nice to just be able to image them. Thanks, -Drew

5 4

which kernel for AMD Sempron processor?
by Tom 03 Oct '05

03 Oct '05

Hi all, Is it ok to use the i686 kernel in an AMD Sempron or should I be using another? regards tom

5 8

Re: [which kernel for AMD Sempron processor?
by Peter Farrow 03 Oct '05

03 Oct '05

Agreed: Should have read "socket A" semprons, since these are the most common currently although rapidly disappearing... >*1* type of Sempron is an Athlon XP processor, the Socket-462 >versions. With the Socket-754, it is an Athlon 64, although >most have their 64-bit functions disabled. Only the lastest, >specifically branded Sempron 64 have the same, full >compatibility as their more expensive brothers. Bryan J. Smith wrote: >Tom <admin(a)homemachine.net> wrote: > > >>Hi all, >>Is it ok to use the i686 kernel in an AMD Sempron or should >>I be using another? >> >> > >To begin, know there are *3* different types of Semprons ... > >1. All Socket-462 Semprons are 32-bit only >They are Throughbred/Barton core (last rev Athlon XP) > >2. Most Socket-754 Semprons are 32-bit only >They are typically Newcastle core (mid-rev Athlon 64) with >the 52-bit addressing (PAE52) and other protions disabled > >3. New Socket-754 Sempron 64s are PAE52, 64-bit reg, etc... >Largely as an answer to Intel releasing the P4-Celeron EM64T, >AMD has stopped disabling the functionality of the cores. A >few are even newer Winchester (Rev. D), although I haven't >seen a Venice (Rev. E -- SSE support) Sempron 64 > >Now regarding the kernel, know these facts ... > >A. Athlon optimizations -- especially in GCC 3.3 (3.4 seems >to be much better) -- are not always stable (at least with >-O3). So even if you load an Athlon optimized kernel, GCC is >typically using -O2. On kernel 2.4, you'll see maybe a 5-15% >performance improvement. > >B. Linux Kernel 2.6 now adds [32-bit] Athlon optimizations >as a _dynamic_, modular support in the _stock_ i686 kernel. >There is little benefit to building a separate Athlon kernel, >as I've tried, and seen _no_ noticable improvement. > >C. If you load a x86-64 kernel, most of those _are_ already >optimized for Athlon architecture because they are the most >common. The 32-bit and 64-bit Athlons use the same core >scheduler design (with only a tiny variance), so just going >Linux/x86-64 now defaults to Athlon-optmizations. > >Personal Note: I found that rebuilding kernel 2.6 without >HIGHMEM support (960MiB memory max) increases performance >well over 15%, and the greatest increase possible with any >kernel change. > > >Ignacio Vazquez-Abrams <ivazquez(a)ivazquez.net> wrote: > > >>The i686 kernel is fine. If you're looking for (small) >>speedups then you're better off rebuilding the glibc >>and openssl packages for athlon. >> >> > >Agreed. But be careful in throwing the -O3 switch. Stick >with --target=athlon, which the SPEC file should just use -O2 >by default. > > >Peter Farrow <peter(a)farrows.org> wrote: > > >>The Sempron is essentislly an Athlon XP processor, so I >>would use the Athlon kernel... >> >> > >*1* type of Sempron is an Athlon XP processor, the Socket-462 >versions. With the Socket-754, it is an Athlon 64, although >most have their 64-bit functions disabled. Only the lastest, >specifically branded Sempron 64 have the same, full >compatibility as their more expensive brothers. > > >Peter Farrow <peter(a)farrows.org> wrote: > > >>Note: In some rare cases I have seen Athlon systems hang >>at boot on i686 kernels, and vice versa, this seems to be >>system board chipset related.....so don't take out any >>kernels you intend to replace until you have seen the >>system boot reliably.. >> >> > >There were various errata with Athlons (not always AMD's >fault), including: >- Intel changing the i686 ISA slightly with the P3/P4 (breaks >even i486 compatibility, sometimes even i586/Pentium). >- Intel 4M paging mode (AGP coherency issue in the Athlon's >on-board AGPgart, long, long story -- 4K paging is no lower >performance on Athlon, so 4M should never be used) >- ViA ATA and other southbridge peripherals failing >- SiS I2C compatibility issues >- Many others > >Nothing unheard of and not without some equivalents in the >Intel world (such as ICH ATA issues), but still notable. > > >Karanbir Singh <mail-lists(a)karan.org> wrote: > > >>There is no Athlon kernel in CentOS4.... as Ignacio has >>pointed out, should you need that small performance boost, >>then build yourself. >> >> > >If you have less than 1GiB RAM, then rebuilding without >HIGHMEM support would yield a much greater boost. > >I had this discussion over on the Fedora-Devel list back >after Fedora Core 2 came out and I complained about not >having a separate Athlon kernel. In the 2.6 kernel, the i686 >kernel dynamically loads support for Athlon optimizations, >instead of having a separate kernel. > >Sure enough, the boost I saw was because I removed HIGHMEM >support. I rebuilt the exact same configs with i686 and >Athlon and saw no difference whatsoever on kernel 2.6. >Apparently Linus concept of making optimizations more dynamic >for various i686 ISA compatible processors (C3/Geode, Athlon, >even P4, etc...) really works. > > >Tom <admin(a)homemachine.net> wrote: > > >>Ah yes, that's why I asked as I couldn't find an Athlon >>kernel for 4.1 :) Will there be one? >> >> > >Red Hat will not be adding one in the FC2+/RHEL4+ series >because of their view on the kernel 2.6 modular design. >Given my own testing (despite my initial reluctance), they >are indeed correct. > >I'll try to find the post in the LKML (Linux Kernel Mailing >List) that covers how the dynamic support works in the i686 >kernel. I know from what I've read before, there was just so >much overlap combined with so many i686 variants, there was a >real wish to see a more "core" i686 base with loadable >optimizations for Geode/C3, Athlon, P4, etc... > > > > >

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Discuss October 2005