proxmox-backup-client

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lanepark5033

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Feb 20, 2025
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I installed proxmox-backup-client on a manjaro desktop and ran a backup to a proxmox backup server. The backup ran fine, but the disk I was backing up has very little data but the proxmox-backup-client wants to backup all the empty space. (Single drive {ssd} has 480GB but only about 7% is used.) Is there a way to configure proxmox-backup-client so that only the actual data is backed up ?
(I know I can specify "count=xxx" when running DD to limit the size of the DD. I get the last block number from gparted)
Also I have not updated the Pbs to 4.0 yet.
 
how are you backing up your system? if you are backing up the whole disk using a block-based backup (fidx/image), then trimming the filesystem on it might help.. if you are backing up using file-based backup (didx/pxar) then empty space should not be an issue ;)
 
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I'm backing up a complete disk, it is the only disk in the system so another issue I am working on is building a standalone (USB) bootable system with proxmox-backup-client installed. I have recently pruned the major partition so there is a much larger unallocated space. Have not run another backup yet to verify that the new backup is both quicker and smaller. Will update.
 
ah, I missed the part about the free space being unallocated entirely, not just unused on the file system. in that case, you can either backup your parition(s) instead of the full disk, or ensure that the unallocated space is full of zeroes which don't take up any space in the backup.
 
fabian said:
ah, I missed the part about the free space being unallocated entirely, not just unused on the file system. in that case, you can either backup your parition(s) instead of the full disk, or ensure that the unallocated space is full of zeroes which don't take up any space in the backup.
Click to expand...
Obviously one can not write zeros to an unallocated space, least not as far as I know how. I'm assuming I need to allocate the unused space to a seperate volume and write zeros in it, IIRC there is a utility that will fill a volume with zeros, but for the life of me, I can't remember it's name, any help there ?
Also, if I unallocate the volume after writting zeros will they remain stored in that space ?

lanepark5033 said:
I'm backing up a complete disk, it is the only disk in the system so another issue I am working on is building a standalone (USB) bootable system with proxmox-backup-client installed. I have recently pruned the major partition so there is a much larger unallocated space. Have not run another backup yet to verify that the new backup is both quicker and smaller. Will update.
Click to expand...
I did run another backup to a different "backup-ID" and it did not change the backup time or size, apparently backing up a complete drive (sdx) means just that.
IIRC the process of backing up has 2 features (I like), incremental applied at the backup source and dedup applied at the backup server.
 
lanepark5033 said:
Obviously one can not write zeros to an unallocated space, least not as far as I know how. I'm assuming I need to allocate the unused space to a seperate volume and write zeros in it, IIRC there is a utility that will fill a volume with zeros, but for the life of me, I can't remember it's name, any help there ?
Also, if I unallocate the volume after writting zeros will they remain stored in that space ?


I did run another backup to a different "backup-ID" and it did not change the backup time or size, apparently backing up a complete drive (sdx) means just that.
IIRC the process of backing up has 2 features (I like), incremental applied at the backup source and dedup applied at the backup server.
Click to expand...
I changed the configuration of the single SSD (500GB) system in that the unused space (Over 400GB worth) is a volume containing all zeros. The backup ran the same time as before and was the same size.
Clonezilla runs a LOT faster and only moves the actual data contained on the drive, but does NOT support incremental or dedup.
DD has a feature where I can specify the actual last block, the DD action terminates when that value is reached.
I wish that PBC in a non-PVE enviornment would have such a feature as does DD.
 
I don't think there are any technical blockers to adding skip and count options to the fixed-size backup client mode, would you mind filing a request on bugzilla for that?
 
lanepark5033 said:
Thanks for the heads up, Fabian. I've submitted the bugzilla request as number 5769.
Regards
Lane
Click to expand...
I discovered a better way to move a large disk (500GB) with only 123GB of actual data to a PVE vm.
First I did a 'qemu-img convert -O qcow2 /dev/nvme2n1(A whole disk on a standalone Linux) /mnt/move/disk.qxow2'
the output was stored on a large SSD drive, so moveable to my PVE.
Next I did a 'qemu-img resize --shrink /mnt/move/disk.qcow2 -300G'
next i did a 'gdisk /dev/sdx'
followed in gdisk with a 'r'
then 'b'
then 'p'
then 'w'
If I understand it correctly this rebuilds the gpt partition table of the disk.
next I move the SSD to the PVE
and did 'gm importdisk 113 /mnt/move/disk.qcow2 local-lvm'

There are some understood actions that need to be performed such as mounting the output SSD disk to a /mnt directory and possibly using sudo
for some of the commands. Your mileage may vary.....
 
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