Can someone give some insight if proxmox is using any type of compression for live migration?
at least for the ram transfer, i know qemu has this feature - but it does not seem to be used (see info migrate_capabilities below)
https://git.lierfang.com/proxmox/mirror_qemu/-/blob/v9.0.0/docs/multi-thread-compression.txt
Use multiple thread (de)compression in live migration
Introduction
============
Instead of sending the guest memory directly, this solution will
compress the RAM page before sending; after receiving, the data will
be decompressed. Using compression in live migration can help
to reduce the data transferred about 60%, this is very useful when the
bandwidth is limited, and the total migration time can also be reduced
about 70% in a typical case. In addition to this, the VM downtime can be
reduced about 50%. The benefit depends on data's compressibility in VM.
# info migrate_capabilities
xbzrle: off
rdma-pin-all: off
auto-converge: off
zero-blocks: off
compress: off
events: off
postcopy-ram: off
x-colo: off
release-ram: off
block: off
return-path: off
pause-before-switchover: off
multifd: off
dirty-bitmaps: off
postcopy-blocktime: off
late-block-activate: off
x-ignore-shared: off
validate-uuid: off
background-snapshot: off
zero-copy-send: off
postcopy-preempt: off
switchover-ack: off
dirty-limit: off
regarding disk transfer i don't know if there is some feature in qemu, but at least i know it could dramatically speed up disk transfer across the network, i had opened a bugzilla for that longer time ago
https://bugzilla.proxmox.com/show_bug.cgi?id=4377
at least for the ram transfer, i know qemu has this feature - but it does not seem to be used (see info migrate_capabilities below)
https://git.lierfang.com/proxmox/mirror_qemu/-/blob/v9.0.0/docs/multi-thread-compression.txt
Use multiple thread (de)compression in live migration
Introduction
============
Instead of sending the guest memory directly, this solution will
compress the RAM page before sending; after receiving, the data will
be decompressed. Using compression in live migration can help
to reduce the data transferred about 60%, this is very useful when the
bandwidth is limited, and the total migration time can also be reduced
about 70% in a typical case. In addition to this, the VM downtime can be
reduced about 50%. The benefit depends on data's compressibility in VM.
# info migrate_capabilities
xbzrle: off
rdma-pin-all: off
auto-converge: off
zero-blocks: off
compress: off
events: off
postcopy-ram: off
x-colo: off
release-ram: off
block: off
return-path: off
pause-before-switchover: off
multifd: off
dirty-bitmaps: off
postcopy-blocktime: off
late-block-activate: off
x-ignore-shared: off
validate-uuid: off
background-snapshot: off
zero-copy-send: off
postcopy-preempt: off
switchover-ack: off
dirty-limit: off
regarding disk transfer i don't know if there is some feature in qemu, but at least i know it could dramatically speed up disk transfer across the network, i had opened a bugzilla for that longer time ago
https://bugzilla.proxmox.com/show_bug.cgi?id=4377