From: Sebastian Riemer <sebastian.riemer@profitbricks.com>
To: linux-raid@vger.kernel.org
Subject: Reason for md raid 01 blksize limited to 4 KiB?
Date: Mon, 21 May 2012 10:43:51 +0200 [thread overview]
Message-ID: <4FBA0047.5050208@profitbricks.com> (raw)
Hi list,
I'm wondering why stacking raid1 above raid0 limits the block sizes in
the blkio queue to 4 KiB both read and write.
The max_sectors_kb is at 512. So it's not a matter of limits.
Could someone explain, please? Or could someone pinpoint me to the
related location in the source code?
We've thought of using this for replication via InfiniBand/SRP. 4 KiB
chunks are completely inefficient with SRP. We wanted to do this with
DRBD first, but this is also extremely inefficient, because of chunk
sizes in the blkio queue.
I can reproduce the small 4 KiB chunks also in a file copy benchmark
with raid 01 on ram disks.
Cheers,
Sebastian
next reply other threads:[~2012-05-21 8:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-21 8:43 Sebastian Riemer [this message]
2012-05-21 23:14 ` Reason for md raid 01 blksize limited to 4 KiB? Stan Hoeppner
2012-05-21 23:28 ` NeilBrown
2012-05-25 12:35 ` Sebastian Riemer
2012-05-28 4:05 ` NeilBrown
2012-05-29 9:30 ` Sebastian Riemer
2012-05-29 10:25 ` NeilBrown
2012-05-30 13:03 ` Sebastian Riemer
2012-05-31 5:42 ` NeilBrown
2012-05-31 6:18 ` Yuanhan Liu
2012-05-31 10:26 ` Sebastian Riemer
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