Backup speed KVM vs LXC

[driftux]

LXC has more performance comparing to KVM. But as I read LXC container backup is a quite slow, because it is like a type of the file system backup. I mean you need to copy like all the files with LXC and KVM is just a single huge file.
Could someone tell me if I backup 2TB container of very small files (mail server), how much time I will need to do LXC backup to local mechanic disk comparing to KVM backup time doing it from Proxmox Backup server?
I want to use LXC, but I affraid that backups will take quite long time to do the backup, and the most important thing that it will took a longer to restore.
I want to fire up Proxmox Backup machine on Ceph storage.

 

[oguz]

hi,

if you are doing an online backup of the VM with backup server, it will be likely much faster than the LXC backup (because of dirty bitmap)

using a HDD (i guess that's what you mean by mechanic disk), the speeds will be relatively low in any case.

and the restore speed depends on your read speed.

for a mail server i think i would use a VM, but without too much data a CT can be enough as well. my suggestion is to test and see what works better in your setup (you can create lots of small files in a VM/CT and do a backup)

 

[driftux]

Thanks. I plan that mechanical HDD will contain millions of small files after 3 years. So here is a dilemma, or to have LXC with better performance because servers are quite weak, but have trouble with backup/restore. Or use KVM, and always have lower performance and quicker restore procedure.

I want to imagine the difference. Could we say that 2TB will be backup/restore per 3/3 hours on VM, and 12/12 hours on LXC?