Hi, Currently, proxmox backup are using copy-before-write to have snapshot backup.
This works great until you have a slow or remote storage with higher latencies than the vm storage. This can slowdown a lot the vm is a lot of writes occur when backup is running. (or even can hang the vm if backup storage goes down during the backup) qemu backup support since 1-2 years some kind of local write cache, called "fleecing". When backup is running, if a block is not yet backuped, it's going to a temp local disk image. Some improvements have been made in qemu 7.0, previously only qcow2 was allowed for the temp disk, now it's working with any disk https://github.com/qemu/qemu/commit/af5bcd775f3115e4c1b7715920a67b31b119de30 Could it be possible to implement same king of cache for proxmox backup ? I think qemu implementation is a simple block filter (It's even possible to expose a virtual snasphot), so maybe it could be easy to implement it ? This is really a blocker for me,I can't use pbs because I'm using nvme is production, and a 7200k hdd backup in a remote 200km site with 5ms latency. If I could use temp nvme cache on the hypervisor, it could be wonderfull :) I had opened a bugzilla some week ago with same kind of local cache idea (didn't known about qemu fleecing at this time, seem the way to go) https://bugzilla.proxmox.com/show_bug.cgi?id=4136 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
