* Resync intermittently writes to spare drives, waking them up
@ 2011-04-13 21:10 Rory Jaffe
2011-04-14 8:32 ` David Brown
2011-04-18 0:55 ` NeilBrown
0 siblings, 2 replies; 3+ messages in thread
From: Rory Jaffe @ 2011-04-13 21:10 UTC (permalink / raw)
To: linux-raid
I have a RAID5 array with 4 active devices and two spares. The spares
are normally in sleep mode. I ran a resync with:
echo repair > /sys/devices/virtual/block/md0/md/sync_action
About 20 times (evenly spaced apart) during the resync, the spares
were written to, waking them up. Is that behavior desired? It seems to
me that it's a waste--I don't know why the resync would bother with
the spares.
--Rory
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Resync intermittently writes to spare drives, waking them up
2011-04-13 21:10 Resync intermittently writes to spare drives, waking them up Rory Jaffe
@ 2011-04-14 8:32 ` David Brown
2011-04-18 0:55 ` NeilBrown
1 sibling, 0 replies; 3+ messages in thread
From: David Brown @ 2011-04-14 8:32 UTC (permalink / raw)
To: linux-raid
On 13/04/2011 23:10, Rory Jaffe wrote:
> I have a RAID5 array with 4 active devices and two spares. The spares
> are normally in sleep mode. I ran a resync with:
>
> echo repair> /sys/devices/virtual/block/md0/md/sync_action
>
> About 20 times (evenly spaced apart) during the resync, the spares
> were written to, waking them up. Is that behavior desired? It seems to
> me that it's a waste--I don't know why the resync would bother with
> the spares.
>
This isn't an answer to your question, but I would recommend changing to
a raid 6 with 5 devices and one spare. Raid 6 gives you /much/ better
reliability - you can thing of it as Raid 5 + hot spare with the hot
spare already synchronised.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Resync intermittently writes to spare drives, waking them up
2011-04-13 21:10 Resync intermittently writes to spare drives, waking them up Rory Jaffe
2011-04-14 8:32 ` David Brown
@ 2011-04-18 0:55 ` NeilBrown
1 sibling, 0 replies; 3+ messages in thread
From: NeilBrown @ 2011-04-18 0:55 UTC (permalink / raw)
To: Rory Jaffe; +Cc: linux-raid
On Wed, 13 Apr 2011 14:10:46 -0700 Rory Jaffe <rsjaffe@gmail.com> wrote:
> I have a RAID5 array with 4 active devices and two spares. The spares
> are normally in sleep mode. I ran a resync with:
>
> echo repair > /sys/devices/virtual/block/md0/md/sync_action
>
> About 20 times (evenly spaced apart) during the resync, the spares
> were written to, waking them up. Is that behavior desired? It seems to
> me that it's a waste--I don't know why the resync would bother with
> the spares.
Yes, there is room for optimisation there. It really shouldn't write to
those devices. I guess I should try (again) to fix that.
Thanks for the report.
NeilBrown
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-04-13 21:10 Resync intermittently writes to spare drives, waking them up Rory Jaffe
2011-04-14 8:32 ` David Brown
2011-04-18 0:55 ` NeilBrown
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