Public bug reported: 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. ** Affects: nova Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1478800 Title: Libvirt migrations with rsync are slow Status in OpenStack Compute (nova): New 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. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1478800/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
