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Ko_deZ
n00b
Joined: 18 Sep 2002
Posts: 43
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 Posted: Fri Sep 24, 2004 2:43 pm Post subject: Missing RAID devices? |
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| Hi. I have just moved to RAID5 to get some data security (big boys don't backup, but they cry quite often). What i want is to have to raid devices running on the same three disks. I have made two partitions on all the disks, one 10G and one 190G so that they are exacly the same. I got the big array up and running without problems, but when trying to get the second one up, i realize that i have only one raid device, /dev/md0. That is the only one, so when i want to mkraid /dev/md1, my system can't find it. There is probably a simple solution, but i am unable to find it. What should i do? |
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chickaroo
Tux's lil' helper
Joined: 21 Sep 2004
Posts: 102
Location: #!/usr/bin/girl
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| Posted: Sat Sep 25, 2004 4:10 pm Post subject: |
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hardware or software raid?
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Ko_deZ
n00b
Joined: 18 Sep 2002
Posts: 43
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| Posted: Wed Sep 29, 2004 1:10 pm Post subject: Ko_deZ |
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Software raid.
Here is my raidconf:
| Code: |
raiddev /dev/md0
raid-level 5
nr-raid-disks 3
nr-spare-disks 0
persistent-superblock 1
parity-algorithm left-symmetric
chunk-size 128
device /dev/sda2
raid-disk 0
device /dev/sdb2
raid-disk 1
device /dev/sdc2
raid-disk 2
#raiddev /dev/md1
# raid-level 5
# nr-raid-disks 3
# nr-spare-disks 0
# persistent-superblock 1
# parity-algorithm left-symmetric
# chunk-size 128
# device /dev/sda1
# raid-disk 0
# device /dev/sdb1
# raid-disk 1
# device /dev/sdc1
# raid-disk 2
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As you can see, I have commented out /dev/md1, cause the device does not exist.
Here is my /dev/m* (ls /dev/m*)
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/dev/mcd /dev/mcdx2 /dev/mem /dev/midi01 /dev/midi2 /dev/mixer2
/dev/mcdx /dev/mcdx3 /dev/mga /dev/midi02 /dev/midi3 /dev/mixer3
/dev/mcdx0 /dev/mcdx4 /dev/midi0 /dev/midi03 /dev/mixer /dev/mpu401data
/dev/mcdx1 /dev/md0 /dev/midi00 /dev/midi1 /dev/mixer1 /dev/mpu401stat
/dev/md:
0
/dev/misc:
agpgart psaux
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As you can see, there is only one md device, and that is md0. After what i can understand, it is supposed to be more like "ls /dev/hd*" with a lot of devices listed (even if there is no devices connected).
Please help!
-Ko_deZ- |
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scout
Veteran
Joined: 08 Mar 2003
Posts: 1991
Location: France, Paris en Semaine / Metz le W-E
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| Posted: Thu Sep 30, 2004 1:42 am Post subject: |
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I just had the same problem, and here is my solution:
the kernel only initializes md0 because the other raid arrays do not have their superblock well initialised. To initialise the superblock we should just make a "mkraid --really-force /dev/md1" for example, but we can't, since it complains md1 doesn't exists.
My trick is to make the kernel recognize md1 manually:
you put an option md=1,5,128,0,/dev/sda1,/dev/sdb1,/dev/sdc1 as a kernel parameter in grub/lilo
(the parameters are described in /usr/src/linux/Documentation/md.txt)
Then when you reboot, md1 is recognized, you can "mkraid --really-force /dev/md1" the superblock is initialised and then you can reboot without the md option and the kernel raid autodetection will work if you have set the patition type to fd with fdisk or cfdisk
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