Hi all,
As the subject says, I'm wondering what issuing the "check" command to a
raid array does.
The wiki says it starts a full read of the raid array. However I wonder
if all members, especially the parts of the drives containing the
redundancy information, will be read, and possibly the validity of the
redundancy data will be checked?
A possibly related question is: why did this member turn into "spare"
role? The system was fully functional and in daily use for about a year.
It was declared to be a four drive raid 5 with no spares. If I remember
level 5 correctly there is no single drive for the redundancy data to
avoid bottlenecks, right?
alpha md # mdadm --examine --verbose /dev/sdh2
/dev/sdh2:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : fa8fb033:6312742f:0524501d:5aa24a28
Name : sysresccd:1
Creation Time : Sat Jul 17 02:57:27 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 3904927887 (1862.01 GiB 1999.32 GB)
Array Size : 11714780160 (5586.04 GiB 5997.97 GB)
Used Dev Size : 3904926720 (1862.01 GiB 1999.32 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 172eb49b:03e62242:614d7ed3:1fb25f65
Update Time : Sun Jan 9 19:55:09 2011
Checksum : a991f168 - correct
Events : 34
Layout : left-symmetric
Chunk Size : 512K
Device Role : spare
Array State : AAAA ('A' == active, '.' == missing)
Too bad that 1.2 superblocks don't contain the full array information
like 0.90 did.
Regards,
Christian
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