* does chunksize matter in raid-1?
@ 2005-08-06 4:07 Jeff Breidenbach
2005-08-06 12:44 ` Paul Clements
0 siblings, 1 reply; 3+ messages in thread
From: Jeff Breidenbach @ 2005-08-06 4:07 UTC (permalink / raw)
To: linux-raid
Does chunk size matter *at all* for RAID-1?
mdadm --create /dev/md0 --level=1 --chunk=8 /dev/sdc1 /dev/sdd1
mdadm --create /dev/md0 --level=1 --chunk=128 /dev/sdc1 /dev/sdd1
In my mental model of how RAID works, it can't possibly matter
what my chunk size is whether I've got 1KB files or 1GB files because
no striped reading occurs.
Is my mental model wrong?
-Jeff
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: does chunksize matter in raid-1?
2005-08-06 4:07 does chunksize matter in raid-1? Jeff Breidenbach
@ 2005-08-06 12:44 ` Paul Clements
2005-08-06 17:47 ` J. Ryan Earl
0 siblings, 1 reply; 3+ messages in thread
From: Paul Clements @ 2005-08-06 12:44 UTC (permalink / raw)
To: jeff; +Cc: linux-raid
Jeff Breidenbach wrote:
> Does chunk size matter *at all* for RAID-1?
>
> mdadm --create /dev/md0 --level=1 --chunk=8 /dev/sdc1 /dev/sdd1
> mdadm --create /dev/md0 --level=1 --chunk=128 /dev/sdc1 /dev/sdd1
>
> In my mental model of how RAID works, it can't possibly matter
> what my chunk size is whether I've got 1KB files or 1GB files because
> no striped reading occurs.
>
> Is my mental model wrong?
No, chunk size does not matter for raid1. In fact, some/most? kernels
will print a message to that effect if you specify a chunk size for a
raid1 array.
--
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: does chunksize matter in raid-1?
2005-08-06 12:44 ` Paul Clements
@ 2005-08-06 17:47 ` J. Ryan Earl
0 siblings, 0 replies; 3+ messages in thread
From: J. Ryan Earl @ 2005-08-06 17:47 UTC (permalink / raw)
To: Paul Clements; +Cc: jeff, linux-raid
Paul Clements wrote:
> No, chunk size does not matter for raid1. In fact, some/most? kernels
> will print a message to that effect if you specify a chunk size for a
> raid1 array.
Yet if you use raidtools and /etc/raidtab you must specify chunksize it
to create a RAID1....
In other words, stick to mdadm.
-ryan
^ permalink raw reply [flat|nested] 3+ messages in thread
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2005-08-06 4:07 does chunksize matter in raid-1? Jeff Breidenbach
2005-08-06 12:44 ` Paul Clements
2005-08-06 17:47 ` J. Ryan Earl
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