[PVE-User] Backup Image Size
flavio.stanchina at ies.it
Tue Sep 11 15:09:58 CEST 2012
Christian Cartwright wrote:
> Thank you for the reply.
> The disk image is 250GB
> Windows reading it as 250GB with 207GB Free, then when its backed up Proxmox Backup image is 70GB.
One should never overprovision disk space for a virtual machine (or at
least not by as much as you did here) in the off chance that someday one
might need it. The operating system in the VM will happily sprinkle
blocks here and there sometimes, but it doesn't fill those blocks with
zeros when they are no longer in use; those blocks will not compress
well and you'll end up with an unnecessarily large backup, as you just
It's easy to enlarge the virtual disk or add a new disk --even
temporarily -- when needed. With Proxmox VE 2.x you can even exclude a
virtual disk from backups -- perfect for temporary storage space in the
VM, just make sure that the users know which disk is safe and which one
> I will certainly try SDelete!
Careful with tools that zero the unused portion(s) of your disk(s):
while it will be beneficial for backups, it may also happen to write to
*every* block of your virtual disk and if you're using thin-provisioned
storage (like qcow2, vmdk, or ZFS thin-provisioned vdisks via iSCSI) you
might end up filling it to capacity, depending on how smart it is in
handling zero-filled blocks.
Informatica e Servizi
Trento - Italy
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