It could be a good idea but as Sylvain said how to configure this? Then, what about using scp instead of rsync for a local copy?
----- Original Message ----- From: "Wangpan" <hzwang...@corp.netease.com> To: "OpenStack Development Mailing List" <openstack-dev@lists.openstack.org> Sent: Friday, February 14, 2014 4:52:20 AM Subject: [openstack-dev] [nova] Should we limit the disk IO bandwidth in copy_image while creating new instance? Currently nova doesn't limit the disk IO bandwidth in copy_image() method while creating a new instance, so the other instances on this host may be affected by this high disk IO consuming operation, and some time-sensitive business(e.g RDS instance with heartbeat) may be switched between master and slave. So can we use the `rsync --bwlimit=${bandwidth} src dst` command instead of `cp src dst` while copy_image in create_image() of libvirt driver, the remote image copy operation also can be limited by `rsync --bwlimit=${bandwidth}` or `scp -l=${bandwidth}`, this parameter ${bandwidth} can be a new configuration in nova.conf which allow cloud admin to config it, it's default value is 0 which means no limitation, then the instances on this host will be not affected while a new instance with not cached image is creating. the example codes: nova/virt/libvit/utils.py: diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py index e926d3d..5d7c935 100644 --- a/nova/virt/libvirt/utils.py +++ b/nova/virt/libvirt/utils.py @@ -473,7 +473,10 @@ def copy_image(src, dest, host=None): # sparse files. I.E. holes will not be written to DEST, # rather recreated efficiently. In addition, since # coreutils 8.11, holes can be read efficiently too. - execute('cp', src, dest) + if CONF.mbps_in_copy_image > 0: + execute('rsync', '--bwlimit=%s' % CONF.mbps_in_copy_image * 1024, src, dest) + else: + execute('cp', src, dest) else: dest = "%s:%s" % (host, dest) # Try rsync first as that can compress and create sparse dest files. @@ -484,11 +487,22 @@ def copy_image(src, dest, host=None): # Do a relatively light weight test first, so that we # can fall back to scp, without having run out of space # on the destination for example. - execute('rsync', '--sparse', '--compress', '--dry-run', src, dest) + if CONF.mbps_in_copy_image > 0: + execute('rsync', '--sparse', '--compress', '--dry-run', + '--bwlimit=%s' % CONF.mbps_in_copy_image * 1024, src, dest) + else: + execute('rsync', '--sparse', '--compress', '--dry-run', src, dest) except processutils.ProcessExecutionError: - execute('scp', src, dest) + if CONF.mbps_in_copy_image > 0: + execute('scp', '-l', '%s' % CONF.mbps_in_copy_image * 1024 * 8, src, dest) + else: + execute('scp', src, dest) else: - execute('rsync', '--sparse', '--compress', src, dest) + if CONF.mbps_in_copy_image > 0: + execute('rsync', '--sparse', '--compress', + '--bwlimit=%s' % CONF.mbps_in_copy_image * 1024, src, dest) + else: + execute('rsync', '--sparse', '--compress', src, dest) 2014-02-14 Wangpan _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev