On Tue, 16 Feb 2010 12:20:14 +1100, Neil Brown <neilb@xxxxxxx> wrote:
>> is there any method to find that bad block in context of the raid block
>> device? reading all files is not a good option on large raidsets.
>> level 5, 64k chunk, algorithm 2
>
> It isn't that hard. The code is in drivers/md/raid5.c in the
kernel.....
>
> Rather than trying to describe in general, give me the block number,
> device,
> and "mdadm --examine" of that device, and I'll tell you how I get the
> answer.
the bad block number was 122060740.
[root@raw sqla]mdadm --examine /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 0.91.00
UUID : 9815a2c6:c83a9a53:2a8015ce:9d8e5e8c (local to host raw)
Creation Time : Thu Feb 11 16:01:12 2010
Raid Level : raid6
Used Dev Size : 966060672 (921.31 GiB 989.25 GB)
Array Size : 2898182016 (2763.92 GiB 2967.74 GB)
Raid Devices : 5
Total Devices : 5
Preferred Minor : 2
Reshape pos'n : 974014464 (928.89 GiB 997.39 GB)
New Layout : left-symmetric
Update Time : Tue Feb 16 11:58:37 2010
State : clean
Active Devices : 5
Working Devices : 5
Failed Devices : 0
Spare Devices : 0
Checksum : 16372b12 - correct
Events : 363519
Layout : left-symmetric-6
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 3 2 active sync /dev/sda3
0 0 8 35 0 active sync /dev/sdc3
1 1 8 51 1 active sync /dev/sdd3
2 2 8 3 2 active sync /dev/sda3
3 3 8 83 3 active sync /dev/sdf3
4 4 8 99 4 active /dev/sdg3
thank you.
iam currently reshaping my raid5 to a raid6.
i want to give you a note that i have had the "too-old metadata" problem
with "mdadm - v3.1.1 - 19th November 2009"
commenting out that check started my array again. i thought this should
have been fixed in that version?
what is the right way to stop the reshaping process? kill <pid of mdadm
--grow/assemble> and then mdadm --stop /dev/mdX or just mdadm --stop
/dev/mdX without killing?
other question: what happens when a operating raid5/6 encounters a bad
block at read time? does it just mark the corresponding devices as faild?
> If you were desperate, you could use 'dd' to read each of the chunks
into a
> file, then write a little c/perl/whatever program to xor those files
> together, then use 'dd' to write that file back out the the target
chunk.
>
> NeilBrown
sounds easy so far. mapping blocks to chunks is also easy? and what to do
in a raid6 case?
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