Hi All,
I have run into a most unusual behavior, where mdadm reports a RAID 0
array that is missing a drive as "Active".
Environment:
Ubuntu 8.0.4 Hardy 64-bit
mdadm: 2.6.7
Dual socket quad-core CPU Intel server
8GB RAM
8 SATA II drives
LSI SAS1068 controller
Scenario:
1) I have a RAID 0 created from two drives:
md2 : active raid0 sde1[1] sdd1[0]
488391680 blocks 128k chunks
mdadm -D /dev/md2
/dev/md2:
Version : 00.90
Creation Time : Fri Oct 17 14:24:44 2008
Raid Level : raid0
Array Size : 488391680 (465.77 GiB 500.11 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 2
Persistence : Superblock is persistent
Update Time : Fri Oct 17 14:24:44 2008
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 128K
Number Major Minor RaidDevice State
0 8 49 0 active sync
1 8 65 1 active sync
2) Then I monitor the md device.
mdadm --monitor -1 /dev/md2
3) Then I pull out a hard drive from the RAID 0 out of the system. At
this point, I expect md device to become inactive.
DeviceDisappeared on /dev/md2 Wrong-Level
4) Oddly, no difference is reported in /proc/mdstat:
md2 : active raid0 sde1[1] sdd1[0]
488391680 blocks 128k chunks
5) So I try to run IO, which fails (obviously).
mkfs /dev/md2
mke2fs 1.40.8 (13-Mar-2008)
Warning: could not erase sector 2: Attempt to write block from
filesystem resulted in short write
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
30531584 inodes, 122097920 blocks
6104896 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
3727 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616,
78675968,
102400000
Warning: could not read block 0: Attempt to read block from filesystem
resulted in short read
Warning: could not erase sector 0: Attempt to write block from
filesystem resulted in short write
Writing inode tables: done
Writing superblocks and filesystem accounting information:
Warning, had trouble writing out superblocks.done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
Conclusion: Why does mdadm report a drive failure on RAID 0 but not
make the md device as Inactive or otherwise failed?
Thanks!
-Thomas
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
