Hello, every one:
I had a 4*2T (sdh, sdi, sdj,sdk)raid5 with 128K chuck size and 2048
strip_cache_size. The mdadm 3.2.2, kernel 2.6.38 were used. I wrote a
program to test the write performance for the raid5. While the program
was writing data to the raid5, I unplugged sdk, then I rebooted the
machine. After that, I used “mdadm –assemble --scan” to scan the
array. The output was “not enough to start the array while not clean -
consider --force”. The array was seemed disappeared. Then I used
“mdadm –E /dev/sd[ijh]” to check the superblocks of sdi,sdj and sdh,
the outputs were the following:
# mdadm -E /dev/sd[ijh]
/dev/sdh:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344694 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 2d86ad25:16130eaf:6da00473:60ba7143
Update Time : Tue Sep 11 12:18:55 2012
Checksum : 878b469a - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : AAA. ('A' == active, '.' == missing)
/dev/sdi:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344844 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 7f74fb29:1b2c5c03:1e2b8de1:e25c9e39
Update Time : Tue Sep 11 12:18:55 2012
Checksum : 44dc7bbb - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 1
Array State : AAA. ('A' == active, '.' == missing)
/dev/sdj:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344346 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 5c58dcec:d03b6bd0:738bc5ea:e0c75d33
Update Time : Tue Sep 11 12:18:55 2012
Checksum : d7c438b0 - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : AAA. ('A' == active, '.' == missing)
As the output of “mdadm --assemble --scan ” suggested, I used “mdadm
–assemble –scan --force” to scan the array again. It did work. Again I
used “mdadm –E /dev/sd[ijh]” to see the superblocks of sdi,sdj and
sdh, the outputs were the following:
# mdadm -E /dev/sd[ijh]
/dev/sdh:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344694 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 2d86ad25:16130eaf:6da00473:60ba7143
Update Time : Tue Sep 11 12:18:55 2012
Checksum : 878b469a - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : AAA. ('A' == active, '.' == missing)
/dev/sdi:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344844 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 7f74fb29:1b2c5c03:1e2b8de1:e25c9e39
Update Time : Tue Sep 11 12:18:55 2012
Checksum : 44dc7bbb - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 1
Array State : AAA. ('A' == active, '.' == missing)
/dev/sdj:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : c2e5a470:4a7e42c3:96273d8c:1c8ad2b7
Name : localhost:RAID5 (local to host localhost)
Creation Time : Mon Sep 10 20:17:15 2012
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 310344346 (147.98 GiB 158.90 GB)
Array Size : 931031040 (443.95 GiB 476.69 GB)
Used Dev Size : 310343680 (147.98 GiB 158.90 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 5c58dcec:d03b6bd0:738bc5ea:e0c75d33
Update Time : Tue Sep 11 12:18:55 2012
Checksum : d7c438b0 - correct
Events : 108
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : AAA. ('A' == active, '.' == missing)
There was basically nothing inconsistent between the two outputs,
except that the state of “sdh” in the former output was “active”,
while in the latter was “clean”.
What was the problem? Can any one help me?
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