How much free space is needed to backup VM/LXC ?

[why-be-banned]

How much free space is needed to backup VM/LXC ?
I have my PVE system installed on hard disk A, all VM/LXC installed on hard disk B, and backups on smb storage. So when I back up the VM/LXC to smb storage, how much free space is needed on hard disk A for a successful backup?

INFO: starting new backup job: vzdump 119 --storage smb-f --notification-mode auto --remove 0 --node x2 --compress zstd --mode snapshot --notes-template '{{guestname}}'
INFO: filesystem type on dumpdir is 'cifs' -using /var/tmp/vzdumptmp7708_119 for temporary files
INFO: Starting Backup of VM 119 (lxc)
INFO: Backup started at 2025-02-02 13:22:38
INFO: status = running
INFO: CT Name: x2-docker
INFO: including mount point rootfs ('/') in backup
INFO: mode failure - some volumes do not support snapshots
INFO: trying 'suspend' mode instead
INFO: backup mode: suspend
INFO: ionice priority: 7
INFO: CT Name: x2-docker
INFO: including mount point rootfs ('/') in backup
INFO: starting first sync /proc/4187/root/ to /var/tmp/vzdumptmp7708_119
ERROR: rsync: [receiver] write failed on "/var/tmp/vzdumptmp7708_119/data/home-assistant/home-assistant-arm64.tar": No space left on device (28)
ERROR: rsync error: error in file IO (code 11) at receiver.c(380) [receiver=3.2.7]
ERROR: rsync: [sender] write error: Broken pipe (32)
ERROR: Backup of VM 119 failed - command 'rsync --stats -h -X -A --numeric-ids -aH --delete --no-whole-file --sparse --one-file-system --relative '--exclude=/tmp/?*' '--exclude=/var/tmp/?*' '--exclude=/var/run/?*.pid' /proc/4187/root//./ /var/tmp/vzdumptmp7708_119' failed: exit code 11
INFO: Failed at 2025-02-02 13:25:06
INFO: Backup job finished with errors
TASK ERROR: job errors

 

[UdoB]

ERROR: rsync: [receiver] write failed on "/var/tmp/vzdumptmp7708_119/data/home-assistant/home-assistant-arm64.tar": No space left on device (28)

It is trying to write that complete .tar to that destination. You need as much free space as your compressed source needs. (Edit: this statement may be wrong...)

Probably you can specify "tmpdir" to point to a location with sufficient space, see: https://pve.proxmox.com/wiki/Backup_and_Restore#vzdump_configuration


Disclaimer: not tested - I do not have this problem...

 

[danielpugh]

realise this is old, but searching and finding only fragments of the same info and here is the latest relevant post.
so with a 10TB volume - to perform the initial backup i need 10TB of additional local storage for vzdump to work? just to hold the temporary files before they are copied to the remote backup location which is even larger to allow for initial snapshots and thereafter incrementals...?
totally get it would need a local tmp area, but wouldnt this be flushed constantly as it copies it to the remote proxmox backup server?
half not expecting an answer given age of original post but would be good to know as i cant find the answer on the admin guide (albeit not sure exactly what to search for so it could be there)...

 

[news]

I only save my main disks, from my vm, efi and my be swap-disk.
Datadisks are copy over other ways!

 

[danielpugh]

I only save my main disks, from my vm, efi and my be swap-disk.
Datadisks are copy over other ways!

ill have to do that. Shame as all the backup software i used in the past doesn't require a local disk equal to the entire system to backup remotely. Maybe i have missed something. Main disk is just a mirrored, but was hoping to have it replicate to a spare on an old pc in shed in case the house burns down.
liking proxmox so far. Does seem to require a lot of over-capacity. migrating a 35GB home assistant VM takes at least 4 attempts for no apparent reason (works on the last attempt without any change).