[PVE-User] Uncompressed backups are compressed?

[Chris Murray]

Thank you Yannis.

 

I see from the forum link [1] that the file is not rdiff friendly. I still think that storing an amount of data inside a smaller file is ‘compression’, regardless of how much is actually used inside the RAW file (is RLE compression still a thing?), but that does answer my question. It’s a shame, because I’ll now have to extract backups as they’re created somehow in order to get them into a state where they can be de-duplicated again. I think many people would appreciate a file format inside which the data is aligned, even if it is out-of-order to a degree. I won’t be the first person who has virtual machines which don’t change much.

 

[1] http://forum.proxmox.com/threads/13475-Proxmox-2-3-new-backup-methode-vma-not-rdiff-friendly

 

From: Yannis Milios [mailto:yannis.milios at gmail.com] 
Sent: 13 November 2014 16:32
To: Chris Murray
Cc: pve-user at pve.proxmox.com
Subject: Re: [PVE-User] Uncompressed backups are compressed?

 

VMA is the new backup format since PVE 2.3.It is uncompressed and it should reflect the actual data occupied inside your vm (not raw file size). Gzip and Lzo are used for compression of this file.

http://pve.proxmox.com/wiki/VMA

 

 

 

 

On Thu, Nov 13, 2014 at 5:57 PM, Chris Murray <chrismurray84 at gmail.com> wrote:

Hi,

 

I may be missing the point here, but when choosing to backup a VM with compression = none, instead of LZO or GZIP, I’d expect an uncompressed file to be produced?

 

I’m trying to backup to a device which will perform block-level dedupe, but I guess that won’t work too well when e.g. a 32GB RAW file turns into a 15.9GB .vma file. Or is alignment preserved despite the difference in file size?

 

Thank you,

Chris


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