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Valin n00b
Joined: 09 Dec 2004 Posts: 3
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Posted: Thu Dec 09, 2004 6:40 pm Post subject: |
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I've setup a 3 drive RAID 0, but Grub refuses to setup.
/boot = /dev/md0
swap = /dev/sda2, /dev/sdb2, /dev/sdc2
/ = /dev/md1
Additionally, the instrustions at the beginning of this topic forget to mention you have to first create the md devices in /dev before you can run mkraid.
The problem I'm getting is that Grub refuses to recognize hd0 to install itself into on the MBR. Can I get around this by installing to the boot partition instead? Even if I try it still whines about not finding anything about my drives in the BIOS...huh? |
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Arainach l33t
Joined: 08 Jul 2004 Posts: 609
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Posted: Fri Dec 17, 2004 9:38 pm Post subject: |
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(Please Delete this Post) |
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icn n00b
Joined: 31 Jan 2005 Posts: 1
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Posted: Mon Jan 31, 2005 11:51 pm Post subject: |
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Is one single 36GB Raptor faster than 2 60GB SATA drives in RAID0? Also is it easy to have both Windows and Gentoo on the same drive with RAID 0 and which one do you install first if its possible? Any help would be appreciated. Thanks. |
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R!tman Veteran
Joined: 18 Dec 2003 Posts: 1303 Location: Zurich, Switzerland
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Posted: Thu Mar 10, 2005 12:07 pm Post subject: |
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I have serious performance problems on my new pc. I set up reiserfs on a raid 5 on 4 sata disks with a chunk size of 64K (mdadm standart). But compared to my old pc with only 1 ata disk (and reiser4) the raid performance is horrible.
My old system:
Code: | # time cat /scratch/big.file > /dev/null
real 0m49.614s
user 0m0.053s
sys 0m7.746s
# du -h /scratch/bigfile
2.2G /scratch/big.file |
My new system:
Code: | # time cat /scratch/big.file > /dev/null
real 0m55.600s
user 0m0.012s
sys 0m4.471s
# du -h /scratch/bigfile
2.2G /scratch/big.file |
Even a single sata drive should be faster than the rather old ata drive. The raid 5 is way too slow in my opinion.
What is really strange though is that:
Old system
Code: | # iozone -s 4096
Iozone: Performance Test of File I/O
Version $Revision: 3.226 $
Compiled for 64 bit mode.
Compiled for 32 bit mode.
Build: linux
Contributors:William Norcott, Don Capps, Isom Crawford, Kirby Collins
Al Slater, Scott Rhine, Mike Wisner, Ken Goss
Steve Landherr, Brad Smith, Mark Kelly, Dr. Alain CYR,
Randy Dunlap, Mark Montague, Dan Million,
Jean-Marc Zucconi, Jeff Blomberg,
Erik Habbinga, Kris Strecker.
Run began: Thu Mar 10 12:43:36 2005
File size set to 4096 KB
Command line used: iozone -s 4096
Output is in Kbytes/sec
Time Resolution = 0.000001 seconds.
Processor cache size set to 1024 Kbytes.
Processor cache line size set to 32 bytes.
File stride size set to 17 * record size.
random random bkwd record stride
KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread
freread
4096 4 104049 314064 512255 486165 397089 266838 392078 385437 394798 278637 286135 468387
451354
iozone test complete. |
New system
Code: | # iozone -s 4096
Iozone: Performance Test of File I/O
Version $Revision: 3.226 $
Compiled for 64 bit mode.
Build: linux-AMD64
Contributors:William Norcott, Don Capps, Isom Crawford, Kirby Collins
Al Slater, Scott Rhine, Mike Wisner, Ken Goss
Steve Landherr, Brad Smith, Mark Kelly, Dr. Alain CYR,
Randy Dunlap, Mark Montague, Dan Million,
Jean-Marc Zucconi, Jeff Blomberg,
Erik Habbinga, Kris Strecker.
Run began: Thu Mar 10 12:27:55 2005
File size set to 4096 KB
Command line used: iozone -s 4096
Output is in Kbytes/sec
Time Resolution = 0.000001 seconds.
Processor cache size set to 1024 Kbytes.
Processor cache line size set to 32 bytes.
File stride size set to 17 * record size.
random random bkwd record stride
KB reclen write rewrite read reread read write read rewrite read fwrite frewrite
fread freread
4096 4 323947 1037443 2026691 2119975 2020731 1160033 1967279 1410868 1952300 297132 985321 15
76018 2020731
iozone test complete. |
Here it seems as the raid would indeed be quite faster. Strange... |
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fatalglitch n00b
Joined: 25 Nov 2003 Posts: 54
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Posted: Mon Mar 14, 2005 10:00 pm Post subject: |
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I haven't read through this whole post, so I apologize if I am repeating, but....
It should be noted, with software raid, there is one thing many people forget about, but is HUGE when is comes to both speed AND redudancy
- Each physical drive should be on a SEPERATE ide bus.
Ok, now I will explain this...
Performance - if both drives are on the same IDE bus....your really not gaining any speed increase by RAID0 (striping) due to the fact that the bus still has a maximum thoroughput, and will not exceed that amount...
Redundancy - this should be obvious. Yes hard drive's do go bad....but what happens when the bus goes bad? This may not be necessary for a desktop system, but for a server setup....this is MAJOR. Bus goes dead, then both your physical drives are gone....and the server crashes.
Just some FYI...
-Tom |
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fatalglitch n00b
Joined: 25 Nov 2003 Posts: 54
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Posted: Mon Mar 14, 2005 10:03 pm Post subject: |
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RAID0 will not stripe across 3 drives...your setup (if using software RAID) would be using 2 physical drives to stripe, and a backup drive...(which would be pointless).
If you have 3 drives, your better off using RAID5, as it gives the benefits of RAID0 as well as the redudancy of RAID1
Check your /etc/raidtab for your setup....
Tom
Valin wrote: | I've setup a 3 drive RAID 0, but Grub refuses to setup.
/boot = /dev/md0
swap = /dev/sda2, /dev/sdb2, /dev/sdc2
/ = /dev/md1
Additionally, the instrustions at the beginning of this topic forget to mention you have to first create the md devices in /dev before you can run mkraid.
The problem I'm getting is that Grub refuses to recognize hd0 to install itself into on the MBR. Can I get around this by installing to the boot partition instead? Even if I try it still whines about not finding anything about my drives in the BIOS...huh? |
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fatalglitch n00b
Joined: 25 Nov 2003 Posts: 54
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Posted: Mon Mar 14, 2005 10:06 pm Post subject: |
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Try doing a simulated hotswap of one of the partitions....software raid will sync both disks based on the most current times in the files.
Hotswapping (simulated!!! do NOT try to do a REAL IDE HOTSWAP) will resync the drives and should remove the "dirty" error.
-Tom
BlackB1rd wrote: | And my problem extends since it's not only the dirty status it returns. It also doesn't seem to update the 'Update time', which is very concerning. I guess that means is doesn't keep the RAID array synchronized? |
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dioxmat Bodhisattva
Joined: 04 May 2002 Posts: 709 Location: /home/mat
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Posted: Mon Mar 14, 2005 10:30 pm Post subject: |
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FWIW, raid 5 software sucks. See this blog entry for some explanations on the subject. |
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BlinkEye Veteran
Joined: 21 Oct 2003 Posts: 1046 Location: Gentoo Forums
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Posted: Tue Apr 05, 2005 4:39 pm Post subject: |
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dioxmat wrote: | FWIW, raid 5 software sucks. See this blog entry for some explanations on the subject. |
i couldn't more agree. i just threw away my partitions and am setting up a raid0 system _________________ Easily backup up your system? klick
Get rid of SSH Brute Force Attempts / Script Kiddies klick
Last edited by BlinkEye on Tue Apr 12, 2005 6:55 pm; edited 1 time in total |
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neo_phani n00b
Joined: 01 Sep 2004 Posts: 67
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Posted: Tue Apr 12, 2005 6:44 pm Post subject: |
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ok i tried this with 2 SATA drives and everything went but when i boot on the new kernel
checking root file system ...
ext2fs_check_if_mount: No such file or directory while determining whether /dev/md2 is mounted
fsck.ext3:NO such file
what could i have done wrong ? How do i fix this without having to do it all over again
Also i noticed i had a xfs in my /etc/fstab for md3 which should be ext3 instead ......please tell me how i can change this ? Can i use the boot cd and mount the /dev/md2 and edit stuff...i am lost
/dev/md0 /boot ext2 noauto,noatime 1 2
/dev/md2 / ext3 noatime 0 1
/dev/hda2 none swap sw,pri=0 0 0
/dev/hdc2 none swap sw,pri=0 0 0
/dev/md3 /home xfs noatime 0 1
/dev/cdroms /cdrom0 /mnt/cdrom iso9660 noauto,ro 0 0
proc /proc proc defaults 0 0
my /etc/raidtab
# /boot (RAID 1)
raiddev /dev/md0
raid-level 1
nr-raid-disks 2
chunk-size 32
persistent-superblock 1
device /dev/sda1
raid-disk 0
device /dev/sdc1
raid-disk 1
# / (RAID 1)
raiddev /dev/md2
raid-level 1
nr-raid-disks 2
chunk-size 32
persistent-superblock 1
device /dev/sda3
raid-disk 0
device /dev/sdc3
raid-disk 1
# /home (RAID 1)
raiddev /dev/md3
raid-level 1
nr-raid-disks 2
chunk-size 32
persistent-superblock 1
device /dev/sda4
raid-disk 0
device /dev/sdc4
raid-disk 1 |
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shakti Guru
Joined: 15 May 2002 Posts: 358 Location: omnipresent
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Posted: Mon Apr 25, 2005 8:10 pm Post subject: cannot determine md version: no MD device file in /dev |
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If you get this error create a script and run it...
Code: | for i in 0 1 2 3 4 5 6 7 8 9 10;
do mknod /dev/md$i b 9 $i;
done |
_________________ Using Gentoo since 2002. |
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sro n00b
Joined: 25 Jan 2004 Posts: 13
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Posted: Tue May 03, 2005 7:32 am Post subject: |
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This HowTo didn't work for me
my setup:
/dev/md0 = /boot, RAID1
/dev/md1 = /, RAID1
/dev/sda2, /dev/sdb2 = SWAP, no RAID
SATA Software Raid, Onboard SATA Controller, using module SATA_NV (compiled into the kernel).
when trying to boot, i'm receiving this error:
Quote: |
ext2fs_check_if_mount: No such file or directory while determining wether /dev/md1 is mounted.
fsck.ext3: No such file or directory while trying to open /dev/md1
/dev/md1:
The superblock could not be read or does not describe a correct ext2 filesystem.
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devfs=nomount gentoo=udev is set in my grub.conf
The /dev/md0 and /dev/md1 device nodes are successfully created by 'md' while booting, but when it's time for the kernel to access root, i'm getting an error as quoted above.
/etc/fstab is correct, the line for /dev/md1 says "ext3".
I'm working on this problem the last 7 days, but can't get my software raid1 booting... |
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BlinkEye Veteran
Joined: 21 Oct 2003 Posts: 1046 Location: Gentoo Forums
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Posted: Tue May 03, 2005 8:10 am Post subject: |
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chroot back and create a kernel with devfs support (do NOT activate "Automount at boot" though). after that boot your system with the following kernel options
i had the same problems. this is udev
after a succesfull boot with devfs you may switch back to udev - it will work. _________________ Easily backup up your system? klick
Get rid of SSH Brute Force Attempts / Script Kiddies klick |
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sro n00b
Joined: 25 Jan 2004 Posts: 13
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Posted: Tue May 03, 2005 9:18 am Post subject: |
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Its working!
I followed your steps - udev is causing this problems.
With devfs support, the system now boots perfectly.
Thank you. |
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dac n00b
Joined: 03 May 2005 Posts: 2
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Posted: Tue May 03, 2005 2:26 pm Post subject: Cannot determine md version: no MD device file in /dev |
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I am new and just learning. Thererfore, I was following the directions when I ran into a problem.
Motherboard is ASUS A8V
I have setup two SATA drives using fdisk.
I run modprobe md
I create my raidtab file. I want to have Raid 1.
# / (RAID 1)
raiddev /dev/md2
raid-level 1
nr-raid-disks 2
chunk-size 32
persistent-superblock 1
device /dev/sda3
raid-disk 0
device /dev/sdb3
raid-disk 1
and then when I run "mkraid /dev/md*" , I get "Cannot determine md version: no MD device file /dev"
Why? |
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sro n00b
Joined: 25 Jan 2004 Posts: 13
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Posted: Tue May 03, 2005 3:45 pm Post subject: |
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running "mkraid /dev/md*" means, you should run "mkraid" for each of your arrays.
example for your RAID1:
mkraid /dev/md2 |
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BlinkEye Veteran
Joined: 21 Oct 2003 Posts: 1046 Location: Gentoo Forums
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Posted: Tue May 03, 2005 4:05 pm Post subject: |
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if this doesn't solve your problem you use udev and MUST do the following:
after that, try
again _________________ Easily backup up your system? klick
Get rid of SSH Brute Force Attempts / Script Kiddies klick |
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dac n00b
Joined: 03 May 2005 Posts: 2
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Posted: Tue May 03, 2005 6:25 pm Post subject: |
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I think that help because it is now syncing. Thanks. |
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tscolari l33t
Joined: 02 May 2004 Posts: 602 Location: curitiba - pr - Brazil
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Posted: Mon May 23, 2005 12:44 pm Post subject: |
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i followed the instructions but now when i tryed to do:
mkraid /dev/md0
i got:
Code: | cannot determine md version: no MD device file in /dev |
ive alread modprobed md
also can I start md# with 1? 0 looks confusing :p _________________ ------------------------------------
Tiago Scolari |
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BlinkEye Veteran
Joined: 21 Oct 2003 Posts: 1046 Location: Gentoo Forums
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Posted: Mon May 23, 2005 6:26 pm Post subject: |
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how about reading my post second last from your post? _________________ Easily backup up your system? klick
Get rid of SSH Brute Force Attempts / Script Kiddies klick |
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fast40x n00b
Joined: 21 Jun 2005 Posts: 4
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Posted: Tue Jun 21, 2005 3:44 pm Post subject: mkraid /dev/md0 says 'cannot determine md version: 6.' |
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I am installing Gentoo 2005.0 over top of my Redhat installation. I copied my /etc/raidtab from my old partition. I ran MAKEDEV md and then mkraid.
mkraid /dev/md0 says "cannot determine md version: 6."
I have tried with and without the boot option DOSCSI.
I read somewhere that someone had a problem with the same output, and ended up fixing it by recompiling without RAID 6.
Is there anything I can do to get this to work? Here is my old raidtab:
Code: | raiddev /dev/md0
raid-level 1
nr-raid-disks 2
chunk-size 64k
persistent-superblock 1
nr-spare-disks 0
device /dev/sda5
raid-disk 0
device /dev/sdb5
raid-disk 1
... ommitted for brevity...
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fast40x n00b
Joined: 21 Jun 2005 Posts: 4
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Posted: Tue Jun 21, 2005 4:35 pm Post subject: |
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I think I have my problem solved.
The first thing I did to start getting me on the right track is:
It was in the instructions, but I missed it.
then I realized I shouldn't be doing the mkraid in the first place, but rather:
after that, mounting the systems was a breeze. |
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kevev n00b
Joined: 05 Jan 2005 Posts: 42 Location: Tejas
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Posted: Thu Jun 30, 2005 12:54 am Post subject: New Tips |
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since this post hasnt been touched in a while I tried using the instructions in the first post with no success.
Here are my steps that did work.
I did everything in the first post except when it says to edit menu.lst you should really edit grub.conf.
When it came to running grub to install the boot loader i had errors. I found a bug report on another site
that helped me. you have to edit /etc/mtab to reflect the actual real physical drive and partition that will
hold the grub stage1. my /etc/mtab stated-->
/dev/md0 /boot *****
I changed it to-->
/dev/hda1 /boot ****
(the stars represent the part of the line I did not change)
this allowed me to run grub-install. I also changed /dev/hda1 to /dev/hdc1 and ran grub-install again
so both drives will have the boot loader. I am hoping this will allow me to still boot if the first drive fails.
Here is the original page with the bug report.
https://bugzilla.redhat.com/bugzilla/long_list.cgi?buglist=138572 _________________ your only as smart as the Computer doing your thinking. |
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JeffBlair Apprentice
Joined: 23 May 2003 Posts: 175 Location: USA, Lone star state
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Posted: Wed Jul 13, 2005 5:46 pm Post subject: |
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Got a question for y'all. I am about to get a new server. It has 4 SCSI 9.1G HDD's right now. Later on I am going to add 18.2G. I was wondering 2 things. One, can I swap out the 4 drives and replace them with 6 new ones? I know if I swap out 1 at a time it should rebuild the RAID, right? Also, could you look at what I think the config should be for the 4 drives.
Code: |
-------------cfdisk
sda1 512 /boot RAID 1
sda2 200M / RAID 5
sda3 3G /var RAID 5
sda5 3G /home RAID 5
sda6 500M /tmp RAID 5
sda7 * /usr RAID 5
sdb1 512 /boot RAID 1
sdb2 200M / RAID 5
sdb3 3G /var RAID 5
sdb5 3G /home RAID 5
sdb6 500M /tmp RAID 5
sdb7 * /usr RAID 5
sdc1 512 swap NO RAID
sdc2 200M / RAID 5
sdc3 3G /var RAID 5
sdc5 3G /home RAID 5
sdc6 500M /tmp RAID 5
sdc7 * /usr RAID 5
sdd1 512 swap NO RAID
sdd2 200M / RAID 5
sdd3 3G /var RAID 5
sdd5 3G /home RAID 5
sdd6 500M /tmp RAID 5
sdd7 * /usr RAID 5
-------------- /etc/raidtab
# /boot (RAID 1)
raiddev /dev/md0
raid-level 1
nr-raid-disks 2
chunk-size 32
persistent-superblock 1
device /dev/sda1
raid-disk 0
device /dev/sdb1
raid-disk 1
# / (RAID 5)
raiddev /dev/md1
raid-level 5
nr-raid-disks 4
persistent-superblock 1
chunk-size 32
parity-algorithm right-symmetric
device /dev/sda2
raid-disk 0
device /dev/sdb2
raid-disk 1
device /dev/sdc2
raid-disk 2
device /dev/sdd2
raid-disk 3
# /var (RAID 5)
raiddev /dev/md2
raid-level 5
nr-raid-disks 4
persistent-superblock 1
chunk-size 32
parity-algorithm right-symmetric
device /dev/sda3
raid-disk 0
device /dev/sdb3
raid-disk 1
device /dev/sdc3
raid-disk 2
device /dev/sdd3
raid-disk 3
# /home (RAID 5)
raiddev /dev/md3
raid-level 5
nr-raid-disks 4
persistent-superblock 1
chunk-size 32
parity-algorithm right-symmetric
device /dev/sda5
raid-disk 0
device /dev/sdb5
raid-disk 1
device /dev/sdc5
raid-disk 2
device /dev/sdd5
raid-disk 3
# /tmp (RAID 5)
raiddev /dev/md4
raid-level 5
nr-raid-disks 4
persistent-superblock 1
chunk-size 32
parity-algorithm right-symmetric
device /dev/sda6
raid-disk 0
device /dev/sdb6
raid-disk 1
device /dev/sdc6
raid-disk 2
device /dev/sdd6
raid-disk 3
# /usr (RAID 5)
raiddev /dev/md5
raid-level 5
nr-raid-disks 4
persistent-superblock 1
chunk-size 32
parity-algorithm right-symmetric
device /dev/sda7
raid-disk 0
device /dev/sdb7
raid-disk 1
device /dev/sdc7
raid-disk 2
device /dev/sdd7
raid-disk 3
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I am guessing I can just add on the other 2 drives later on when I get them. Also, is it posible to do LVM on top of this? If so, how would I do it? Thanks a lot. |
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devilrick n00b
Joined: 21 Feb 2005 Posts: 61 Location: The oh so great South East of England
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Posted: Wed Sep 28, 2005 1:58 pm Post subject: root partition |
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I have followed this how-to word for word and everything has gone smoothly, until it came to rebooting into the new kernel.
I have setup grub on a mirrored boot partition which is found and the kernel loads, but upon loading the striped root partition a kernel panic occurs where it cannot open root device "md2".
kernel support is built in for raid mirrored and striped and so is reiserfs (my only file system type).
Running 2.6 kernel.
The striped raid volume works on the livecd after appropriate MAKEDEV modprove md and mkraid and can be accessed after mounting, so it looks like a kernel problem although I can't think what I am missing.
Any ideas?
Thanks. _________________ Today is good, for I am a part of it. |
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