Re: [libvirt-users] Adjust disk image migration (NBD)
On 14.02.2014 10:40, Joaquim Barrera wrote:
Hi all,
As I am doing some tests with qemu, I realized that the way it does
'migrate -i tcp:DEST:444' is not the same as 'libvirt migrate
--copy-storage-inc'. Basically qemu uses the same stream as RAM
migration and libvirt takes advantage of NBD transfer.
With virsh migrate-setspeed I observed that one can only control the
transfer throughput of RAM, but not disk synchronization. At least this
is what I can see in bmon when doing a migration with incremental copy.
The question is: Am I missing something or it is not implemented?
Thank you guys!
I think this is actually a qemu bug. Libvirt passes the correct values:
2014-02-14 10:52:08.010+0000: 27701: debug : qemuMonitorIOWrite:504 :
QEMU_MONITOR_IO_WRITE: mon=0x7f06cc00ea20
buf={"execute":"drive-mirror","arguments":{"device":"drive-virtio-disk0","target":"nbd:masina:49153:exportname=drive-virtio-disk0","speed":1048576,"sync":"full","mode":"existing"},"id":"libvirt-15"}
...
2014-02-14 10:53:51.169+0000: 27701: debug : qemuMonitorIOWrite:504 :
QEMU_MONITOR_IO_WRITE: mon=0x7f06cc00ea20
buf={"execute":"migrate_set_speed","arguments":{"value":1048576},"id":"libvirt-221"}
2014-02-14 10:53:51.204+0000: 27701: debug : qemuMonitorIOWrite:504 :
QEMU_MONITOR_IO_WRITE: mon=0x7f06cc00ea20
buf={"execute":"migrate","arguments":{"detach":true,"blk":false,"inc":false,"uri":"fd:migrate"},"id":"libvirt-223"}
However I observe what you do - disk migration is not shaped, while internal state is.
Michal