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Old 11-17-2009, 12:21 PM   #1
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Hot Spare in Raid


Is it possible to create a Hot spare in raid levels. I need to create a hot spare for a meta device, if any disks in that fails, automatically hot spare disk come into position of failed disk.

Last edited by eldo; 11-17-2009 at 12:22 PM. Reason: raid, linux,
Old 11-17-2009, 12:32 PM   #2
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Yes assuming you're talking about software RAID.

Type "man mdadm" and have a look at the "-x" option.
Old 11-17-2009, 01:04 PM   #3
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Originally Posted by jlightner View Post
Yes assuming you're talking about software RAID.

Type "man mdadm" and have a look at the "-x" option.

I stop a meta device using mdadm -S /dev/md1

after that I tried to start again using

mdadm -As /dev/md1

mdadm: /dev/md1 not identified in config file.

so what is the config file, and how we can make entries in that file.
Old 11-21-2009, 01:09 PM   #4
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can be:

You list devices used, raid level, stuff you would tell it when starting an array with mdadm.
DEVICES /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
ARRAY /dev/md0 devices=/dev/sd[bcdef]1 level=raid5 num-devices=5 metadata=0.90 UUID=665cd099:7ae19af3:87cb1de4:fe062f1b

Simple raid5 config file.

Hot spares are allowed.

If I remember, you can add a spare drive by adding a drive to an array but only telling it to use less than it has (/dev/sda /dev/sdb /dev/sdb 2 drives)

man mdadm
man mdadm.conf
google mdadm spares


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