* Raid5 Read stats for parity cal...
@ 2009-09-17 0:13 Linux Raid Study
2009-09-17 0:20 ` Majed B.
2009-09-17 2:38 ` Neil Brown
0 siblings, 2 replies; 3+ messages in thread
From: Linux Raid Study @ 2009-09-17 0:13 UTC (permalink / raw)
To: linux-raid
Hello:
I understand that parity calculations are not done as part of Raid5
read operation in normal running conditions.
However, it would be done during disk failure or when a sector is bad.
Is there a way (any stats) available to see if parity cal are done
when sector is bad (since this is not as obvious as a disk fail...)
Thanks!
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Raid5 Read stats for parity cal...
2009-09-17 0:13 Raid5 Read stats for parity cal Linux Raid Study
@ 2009-09-17 0:20 ` Majed B.
2009-09-17 2:38 ` Neil Brown
1 sibling, 0 replies; 3+ messages in thread
From: Majed B. @ 2009-09-17 0:20 UTC (permalink / raw)
To: Linux Raid Study; +Cc: linux-raid
You can force an array check by writing "check" (without double
quotes) to a file named "sync_action" found in /proc/sys
Read this for further details: http://linux.die.net/man/4/md
You can run that check at any time, not just when there's a problem.
On Thu, Sep 17, 2009 at 3:13 AM, Linux Raid Study
<linuxraid.study@gmail.com> wrote:
> Hello:
>
> I understand that parity calculations are not done as part of Raid5
> read operation in normal running conditions.
>
> However, it would be done during disk failure or when a sector is bad.
> Is there a way (any stats) available to see if parity cal are done
> when sector is bad (since this is not as obvious as a disk fail...)
>
> Thanks!
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
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>
--
Majed B.
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: Raid5 Read stats for parity cal...
2009-09-17 0:13 Raid5 Read stats for parity cal Linux Raid Study
2009-09-17 0:20 ` Majed B.
@ 2009-09-17 2:38 ` Neil Brown
1 sibling, 0 replies; 3+ messages in thread
From: Neil Brown @ 2009-09-17 2:38 UTC (permalink / raw)
To: Linux Raid Study; +Cc: linux-raid
On Wednesday September 16, linuxraid.study@gmail.com wrote:
> Hello:
>
> I understand that parity calculations are not done as part of Raid5
> read operation in normal running conditions.
Correct.
>
> However, it would be done during disk failure or when a sector is bad.
Also correct.
> Is there a way (any stats) available to see if parity cal are done
> when sector is bad (since this is not as obvious as a disk fail...)
>
Maybe you want
/sys/block/mdX/md/dev-YYY/errors
which counts the number of sectors for which md found a read error and
had to generate correct data using parity, and then wrote that correct
data back.
NeilBrown
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-09-17 0:13 Raid5 Read stats for parity cal Linux Raid Study
2009-09-17 0:20 ` Majed B.
2009-09-17 2:38 ` Neil Brown
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