Re: Strange behaviour on "toy array"

[Patrik Jonsson <patrik@ucolick.org>]

Ok, so I did as Guy suggested, and tried to write to the array after 
failing more than one disk. It says:

[root@localhost raidtest]# echo test > junk/test
-bash: junk/test: Read-only file system

so that's at least an indication that not all is well. The syslog contains:

May 16 22:49:31 localhost kernel: raid5: Disk failure on loop2, 
disabling device. Operation continuing on 3 devices
May 16 22:49:31 localhost kernel: RAID5 conf printout:
May 16 22:49:31 localhost kernel:  --- rd:5 wd:3 fd:2
May 16 22:49:31 localhost kernel:  disk 1, o:1, dev:loop1
May 16 22:49:31 localhost kernel:  disk 2, o:0, dev:loop2
May 16 22:49:31 localhost kernel:  disk 3, o:1, dev:loop3
May 16 22:49:31 localhost kernel:  disk 4, o:1, dev:loop4
May 16 22:49:31 localhost kernel: RAID5 conf printout:
May 16 22:49:31 localhost kernel:  --- rd:5 wd:3 fd:2
May 16 22:49:31 localhost kernel:  disk 1, o:1, dev:loop1
May 16 22:49:31 localhost kernel:  disk 3, o:1, dev:loop3
May 16 22:49:31 localhost kernel:  disk 4, o:1, dev:loop4
May 16 22:49:39 localhost kernel: Buffer I/O error on device md0, 
logical block 112
May 16 22:49:39 localhost kernel: lost page write due to I/O error on md0
May 16 22:49:39 localhost kernel: Aborting journal on device md0.
May 16 22:49:44 localhost kernel: ext3_abort called.
May 16 22:49:44 localhost kernel: EXT3-fs error (device md0): 
ext3_journal_start_sb: Detected aborted journal
May 16 22:49:44 localhost kernel: Remounting filesystem read-only
May 16 22:50:14 localhost kernel: Buffer I/O error on device md0, 
logical block 19
May 16 22:50:14 localhost kernel: lost page write due to I/O error on md0

So I guess I'm happy with that, remounting to read-only seems smart, 
that way the disks aren't messed up more.
Now I added the disks back with

mdadm --add /dev/loop0
mdadm --add /dev/loop2

and the (actual hard-) drive started chugging, the md0_raid5 process is 
sucking cpu and I don't know what it's trying to do... the system has 
become unresponsive, but the drive is still ticking. Is hot-adding the 
drives back in a bad thing to do?

This is educational, at least... :-)

/Patrik

Guy wrote:

>My guess is it will not change state until it needs to access a disk.
>So, try some writes!
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