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Where is the LVM config stored?
by WipeOut 04 Apr '07

04 Apr '07

Hi, I am trying to migrate one of my systems to a VMware virtual machine.. The PC is an IDE drive using LVM and the virtual machine is a SCSI drive using ordinary partitions.. Basically I rsynced the entire filesystem from the physical to the virtual machine and that seemed to work just fine.. I installed grub onto the drive in the virtual machine and its booting fine.. The problem comes when the new system trys to scan for the LVM setup that was on the previous PC.. I thought it would scan the drive, and seen that there are no LVM partitions and move on but it doesn't it has a kernel panic and flashes the cap lock and scroll lock LED's on the keyboard.. Obviously somewhere its being told there should be an LVM partition or its being told to scan hda rather than sda.. I have checked the grub.conf and fstab files and they are all right for the new drive setup.. So where is the LVM config? How do I tell it there are now LVM volumes that need to be accessed? Thanks..

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Dell Perc 4dc
by Jon 04 Apr '07

04 Apr '07

Hello, Is the dell perc 4dc raid card supported by centos 4 and does it work reliably? thanks Jon

2 1

software raid
by Dave 04 Apr '07

04 Apr '07

Hello, I've got a 4.4 box that i'd like to implement software raid on. Does anyone have any experiences with this? Thanks. Dave.

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changing motherboards. kernel panic.
by Erick Perez 04 Apr '07

04 Apr '07

Hi, I just changed the motherboard of a centos 4.4 installation for a new one. this new one has a SIS chipset. Now when i boot from the hard disk i get a kernel panic (unable to find root, no hdd found , etc) I have identified the module I need to load to make centos "see" the disks. Now the question is what do I need to modify in my existing installation, to tell centos to use the new sis module and to *not* use the old intel? Thanks, -- ------------------------------------------------------------ Erick Perez ------------------------------------------------------------

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Page cache flushing algorithm question
by Mark Hull-Richter 03 Apr '07

03 Apr '07

I have been studying this for the last several days, and the one thing that leaps out at me is that the page cache always flushes one page at a time. Always. To some extent, there is justification for this - what has to happen for each page that gets flushed depends in part on what file system is being written to and whether or not there is a function for that file system to handle the pages. However, as far as I can tell, if the mapping data for a page does not exist (mapping->a_ops->writepage == NULL), it is handed to mpage_writepage() for buffer management and i/o submission, whereas almost all of the file systems that do map this function map it to block_write_full_page. These two functions use completely different algorithms for flushing a page from the cache, or at least it sure looks that way. (This figures, because if the file system didn't buffer the pages, the kernel has to do it, whereas if the file system did, the flush is much simpler.) (The only ones that don't use block_write_full_page are reiserfs, which does some interesting things with small files, and the networked file systems, which don't write to a disk file per se.) My question is, is it feasible to tweak these functions so that it becomes possible to flush multiple pages at one time (with one function), or is that too large/complex a change to be worth the effort (which would be considerable)? This might be OT since it is a kernel question, but what the heck.... :-) Thanks. Mark Hull-Richter, Linux Kernel Engineer DATAllegro (www.datallegro.com) 85 Enterprise, Second Floor, Aliso Viejo, CA 92656 949-680-3082 - Office 949-330-7691 - fax

1 0

Pronounced...?
by Miark 03 Apr '07

03 Apr '07

Is CentOS pronounced as a word, or as cent-oh-es? Miark

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Re: [CentOS] where are debuginfo packages for CentOS 4.4?
by David Thompson 03 Apr '07

03 Apr '07

Peter Kjellstrom wrote: >On Tuesday 03 April 2007, David Thompson wrote: >> I checked all the usual suspects without success. >> >> Specifically, I'm looking for debuginfo packages for the updates kernels. > >http://vault.centos.org/ is where old dists and debuginfo lives. It's also= >=20 >mirrored on my mirror (http://mirror.nsc.liu.se/) Interesting. I tried downloading these from vault.centos.org, and I'm getting errors. For example: % rpm -qlp kernel-debuginfo-2.6.9-42.0.10.EL.i686.rpm error: kernel-debuginfo-2.6.9-42.0.10.EL.i686.rpm: MD5 digest: BAD Expected(e7a7cea1d30212b95860dcc7d7ec5992) != (9a990ce2663ea4b93198d2b51bf9b123) Is there something I'm supposed to know that I don't? Can anyone confirm this? Thanks. Dave PS - For comparison, my md5sum on that file is: % md5sum kernel-debuginfo-2.6.9-42.0.10.EL.i686.rpm cc0797735ef3eda448a28bc0922e4584 kernel-debuginfo-2.6.9-42.0.10.EL.i686.rpm

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max RAM support on CENTOS 4.3 (32 bits) ???
by mcclnx mcc 03 Apr '07

03 Apr '07

we have DELL 6800 server with 20GB RAM in it. We like to expand it to 64 GB. I checked Redhat web site and it say max memory is "Architecture & system dependent". Does anyone know what is Max RAM Redhat CENTOS 4.3 (32 bits) support? Thanks. ___________________________________________________ 您的生活即時通－溝通、娛樂、生活、工作一次搞定！ http://messenger.yahoo.com.tw/

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where are debuginfo packages for CentOS 4.4?
by David Thompson 03 Apr '07

03 Apr '07

I checked all the usual suspects without success. Specifically, I'm looking for debuginfo packages for the updates kernels. Thanks much, Dave Thompson UW-Madison

2 1

NTP
by Mike 03 Apr '07

03 Apr '07

Greets! Ok. I'm looking at a client that needs to keep their server time close as reasonably possible (within a minute) of the actual time of day. I've installed the RPM for NTP and I'm looking for tips on what the simplest setup should be, ie: What server(s) should I be using for sync? Should I just run it from a cron every 20 minutes or so? thx. Mike

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