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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 --

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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

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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

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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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RE: [CentOS] mdadm quandary
by tagarsi, arun 03 Oct '05

03 Oct '05

Hello, Ok I managed to fix this myself using the mdadm options in /etc/mdadm.conf Many thanks Arun -----Original Message----- From: centos-bounces(a)centos.org [mailto:centos-bounces@centos.org]On Behalf Of Arun Tagarsi Sent: Sunday, October 02, 2005 1:10 PM To: CentOS mailing list Subject: [CentOS] mdadm quandary Hello, I wonder if has seen a problem of the sorts I am describing as at the moment it is driving me nuts. We have an array of LSI disks (Hardware Raid 5) which are attached to a Linux node. The Node has a LSI929 dual fibre channel card that has a channel attached to controller A and B of the array. So we have a list of devices under /proc/partitions mapping what we are expecting to see , for example the devices /dev/sdd1 (A) and /dev/sdx1 (B ) would form a raid 0 device under linux to make a file system slightly under 1TB. This file system was created using the older mkraid utils at the time but has been in production for over a year. This node and the array unfortunately had a power outage and the resulting problem faced by us is the following. The raid start up fails with as it cannot find a device /dev/sdai1 . This device is not part of the /etc/raidtab but is a normal device defined in the /dev directory. There are no references to the /dev/sdai1 device in /proc/partitions at all . All devices expected as /dev/sdd1 and /dev/sdx1 are listed and show the expected sizes. so I presume these are the only devices that the Linux box would be able to work with. If I run a mdadm --examine of the /dev/sdd1 it shows me that indeed /dev/sdd1 and it is lun 0 of the MD device but it also has references to the /dev/sdai1 device. The mdadm --examine /dev/sdx1 shows up as /dev/sdai1 and is lun 1 of the MD device. This is where I am totally confused and I hope I was able to explain the problem . Is there a way to change the super block from referencing sdai1 to sdx1? without compromising the array . The data on the array we suspect is intact and would take a great deal of time to restore. Thanks for your time. Arun -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.9/116 - Release Date: 9/30/2005 _______________________________________________ CentOS mailing list CentOS(a)centos.org http://lists.centos.org/mailman/listinfo/centos

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Yum update slow on CentOS 4.1 x86_64?
by Remco Barendse 03 Oct '05

03 Oct '05

Hi list I have several CentOS 4.1 boxes, but only one is running x86_64 CentOS. yum update on all boxes is really fast, on the x86_64 box it is horribly slow. Even startup and "Setting up Repos" takes minutes to complete. The box is just idling all the time (no load at all) and is connected to an 8 mbit DSL connection. Also the downloading of the headers seems to go very slow, about 1 kb per second or so? I tested the internet connection (did wget on an 700 mb ISO image) which downloaded at near max speed so I am sortof ruling out the connection. Top doesn't show any load when yum is running, nor is anything eating any cpu cycles. Ideas anyone?

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question on firewire support and centosplus
by Joe Landman 02 Oct '05

02 Oct '05

Hi folks: Firewire was not supported in 4.0 due to the upstream provider not including it. Is it in 4.1? Or is it still out of the mainline upstream kernel provider? What about centosplus? Centosplus has been listed as unsupported. I presume this means that they are/were one-off builds with missing functionality (e.g. xfs, etc), and are not updated. Is this the case? I am looking at this for an important server, and I want to make sure that if we switch to the centosplus kernel that we haven't messed up the rest of the package support, or major kernel bugfixes. The reason I am curious about firewire is that I would like to use the firewire interface rather than the USB interface for our backup drives. Its not much faster, just fewer context switches (e.g. lower server load). Thanks. Joe -- Joe Landman landman(a)scalableinformatics.com http://www.scalableinformatics.com

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scsi tape drive problems
by James B. Byrne 02 Oct '05

02 Oct '05

I am experimenting with a scsi2 HP SureStore DAT24 attached as an external device to an Intel P4 system. I am attempting to create a raw disk image of a dds2 tape made on a non linux system. My immediate problem is that I am trying to terminate a dd process and having no luck. dd was invoked thus: dd if=/dev/nst1 of=/tmp/disk.dds2.img bs=512 & pid=$! a ps reveals this: ps PID TTY TIME CMD 1936 pts/0 00:00:00 bash 2034 pts/0 00:00:15 dd 2093 pts/0 00:00:00 ps a call to kill has no apparent effect: kill -s SIGKILL 2034 ps PID TTY TIME CMD 1936 pts/0 00:00:00 bash 2034 pts/0 00:00:18 dd 2100 pts/0 00:00:00 ps and calls to mt show this: mt -f /dev/nst1 status /dev/nst1: Device or resource busy Short of a reboot, how do I get control of the tape drive back? (once I get the drive back I will have a lot of other questions regarding dd.) Regards, Jim -- . *** e-mail is not a secure channel *** mailto:byrnejb.<token>@harte-lyne.ca James B. Byrne Harte & Lyne Limited vox: +1 905 561 1241 9 Brockley Drive fax: +1 905 561 0757 Hamilton, Ontario <token> = hal Canada L8E 3C3

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Can CentOS 4 be installed from CD1 only?
by Morten 02 Oct '05

02 Oct '05

Hi. I'm installing CentOS far from home and forgot the CDs... I don't have time to download all 4, what are my best options? I can download CD 1 and perhaps 2 - is that enough? Is there a way to install directly over the internet from one of the mirrors? Thanks. Morten

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Red Hat Directory Server SRPMs??
by Alberto 02 Oct '05

02 Oct '05

Hi, Red Hat has released RHDS ( Red Hat Director Server, also know as iplanet/netscape directory server before ) as open source project and is included in Fedora Core as Fedora Directory Server. Any one know where can I get SRPMs for RHEL 3/4?? will be them included on CentOS?? Thanks

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