On 30 May 2013 22:23, Dominic Raferd [off-list ref] wrote:

I am wanting to (re)set up my raid1 array with 1 SSD partition (/dev/sda2)
and 1 'rust' drive partition (/dev/sdb1) , both 240GB. SSD will also have a
very small ext2 partition mounted as /mnt/sda1 (to hold the write-intent
bitmap file).

To get the full speed of the SSD for reads and to maximise speed for writes
I plan to use these settings:

mdadm -C /dev/md0 --level=raid1 -n 2 /dev/sda2 --write-mostly
--write-behind=16384 --bitmap=/mnt/sda1/write-intent-bitmap.file
--bitmap-chunk=256M dev/sdb1

Will this work and be optimal? I am not too bothered about the write-intent
bitmap file but it is not optional I think, hence I set a large chunk size,
could or should it be even larger (or smaller)? Similarly I have tried to
set a high write-behind to speed up writes as much as possible - is 16384
the maximum allowed?

My system has mdadm 3.2.3 and kernel 3.2.26.

Any suggestions gratefully received.

Dominic
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Quick question: Why not a 2 drive "RAID10"?