On 2018-01-31 09:52, Peter Becker wrote:
This is all clear. My question referes to "use the lower devid disk
containing the stripe"
2018-01-31 10:01 GMT+01:00 Anand Jain <anand.j...@oracle.com>:
When a stripe is not present on the read optimized disk it will just
use the lower devid disk containing the stripe (instead of failing back
to the pid based random disk).
Use only one disk (the disk with the lowest devid that containing the
stripe) as fallback should be not a good option imho.
Instead of it should still be used the pid as fallback to distribute
the workload among all available drives.
[stripe to use] = [preffer stripes present on read_mirror_policy
devids] > [fallback to pid % stripe count]
Perhaps I'm not be able to express myself in English or did I misunderstand you?
Unless I'm seriously misunderstanding the commit messages, the primary
purpose of having this as an option at all is for testing. The fact
that it happens to allow semantics similar to MD's write-mostly flag
when dealing with a 2-device raid1 profile is just a bonus.
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