On 09/24/2014 04:57 PM, Brian Rak wrote:
I've been doing some testing of importing virtual machine images, and
I've found that 'rbd import' is at least 2x as slow as 'qemu-img
convert'. Is there anything I can do to speed this process up? I'd
like to use rbd import because it gives me a little additional flexibility.
My test setup was a 40960MB LVM volume, and I used the following two
commands:
rbd import /dev/lvmtest/testvol test
qemu-img convert /dev/lvmtest/testvol rbd:test/test
rbd import took 13 minutes, qemu-img took 5.
I'm at a loss to explain this, I would have expected rbd import to be
faster.
This is with ceph version 0.80.5 (38b73c67d375a2552d8ed67843c8a65c2c0feba6)
rbd import was doing one synchronous I/O after another. Recently import
and export were parallelized according to
--rbd-concurrent-management-ops (default 10), which helps quite a bit.
This will be in
giant.
Josh
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