Offline migration for KVM virtual machine very slow

[rootnetworks]

Hi Guys,


I dot not use any share storage
I'm trying to migrate a virtual machine to another host but it's very slow (Offline mode).


My virtual machine has a 20GB disk(QCOW2) usage is about 3GB in real but take about 15 minutes to complete this migration

I see the NIC run at 11.7 MB/s, on this speed to transfer 3GB file only need 5 minutes (3*1024/11=279s) why PVE take 3 times the time.

Is this by DD pipe? did transfer a lot of empty disk spaces? I'm not sure PVE Is it possible to compress the disk and transfer data for offline mode?



Task Logs:
Virtual Environment 6.4-13
Virtual Machine 104 (test) on node 'DCLAX1A3MC08'
2022-02-13 12:58:38 starting migration of VM 104 to node 'DCLAX1A3MC08' (x.x.x.x)
2022-02-13 12:58:38 found generated disk 'local:104/vm-104-cloudinit.qcow2' (in current VM config)
2022-02-13 12:58:38 found local disk 'local:104/vm-104-disk-0.qcow2' (in current VM config)
2022-02-13 12:58:39 copying local disk images
2022-02-13 12:58:40 Formatting '/var/lib/vz/images/104/vm-104-cloudinit.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=metadata compression_type=zlib size=4194304 lazy_refcounts=off refcount_bits=16
2022-02-13 12:58:40 1104+0 records in
2022-02-13 12:58:40 1104+0 records out
2022-02-13 12:58:40 4521984 bytes (4.5 MB, 4.3 MiB) copied, 0.30285 s, 14.9 MB/s
2022-02-13 12:58:40 33+91 records in
2022-02-13 12:58:40 33+91 records out
2022-02-13 12:58:40 4521984 bytes (4.5 MB, 4.3 MiB) copied, 0.202989 s, 22.3 MB/s
2022-02-13 12:58:40 successfully imported 'local:104/vm-104-cloudinit.qcow2'
2022-02-13 12:58:40 volume 'local:104/vm-104-cloudinit.qcow2' is 'local:104/vm-104-cloudinit.qcow2' on the target
2022-02-13 12:58:41 Formatting '/var/lib/vz/images/104/vm-104-disk-0.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=metadata compression_type=zlib size=21474836480 lazy_refcounts=off refcount_bits=16
2022-02-13 13:13:58 2621904+0 records in
2022-02-13 13:13:58 2621904+0 records out
2022-02-13 13:13:58 10739318784 bytes (11 GB, 10 GiB) copied, 916.531 s, 11.7 MB/s
2022-02-13 13:13:58 89+327582 records in
2022-02-13 13:13:58 89+327582 records out
2022-02-13 13:13:58 10739318784 bytes (11 GB, 10 GiB) copied, 913.805 s, 11.8 MB/s
2022-02-13 13:13:58 successfully imported 'local:104/vm-104-disk-0.qcow2'
2022-02-13 13:13:58 volume 'local:104/vm-104-disk-0.qcow2' is 'local:104/vm-104-disk-0.qcow2' on the target
2022-02-13 13:14:00 migration finished successfully (duration 00:15:22)
TASK OK


Virtual machine Disk:
# du -sh /var/lib/vz/images/104/*
676K /var/lib/vz/images/104/vm-104-cloudinit.qcow2
2.8G /var/lib/vz/images/104/vm-104-disk-0.qcow2

Thank you

 

[rootnetworks]

I know another way backup and use scp transfer backup file to the new host then restore the virtual machine on the new host
Test time < 5 minutes. But need to make a script to do it, not as convenient as GUI