** Changed in: nova
Status: Fix Committed => Fix Released
** Changed in: nova
Milestone: None => liberty-rc1
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https://bugs.launchpad.net/bugs/1478800
Title:
Libvirt migrations with rsync are slow
Status in OpenStack Compute (nova):
Fix Released
Bug description:
Setup:
CentOS 6 + RDO Icehouse (code seems to be the same in trunk)
When doing a nova migrate, the actual backing disk file is copied over with
rsync. I assume the code came from this report
https://bugs.launchpad.net/nova/+bug/1025259
The rsync code uses the "-z" flag for compression. This is probably
fine for cases with lightly used disks. However, with a disk full of
content, it gets very slow. Rsync is not multithreaded so with a
single E5-2670v2 core, we get ~12MB/s transfer speed (CPU bound). With
the modest compression that is achieved this is significantly slower
than no compression.
If possible, some speed test should be done without compression for
disk files with different content. There might not be a reason to use
compression here at all.
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