[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-discuss] Info about compressed images

From: Alberto Garcia
Subject: Re: [Qemu-discuss] Info about compressed images
Date: Wed, 25 Jan 2017 10:21:29 +0100
User-agent: Mutt/1.5.23 (2014-03-12)

On Fri, Jan 13, 2017 at 06:57:53PM +0100, Gianni Costanzi wrote:
> Hi,
> I'm new here and I've started using QEMU when I've started playing
> with Unetlab/EVE Network simulator.
> I have some questions about compression and images with a compressed
> backing file:

I think there's some misunderstanding here about compressed images in
QEMU. I'll try to clarify:

* You create a compressed image with 'qemu-img convert -c'. That is a
  copy of the original image with all the clusters compressed.

* The compression is read-only: QEMU will read the compressed clusters,
  but everything that it writes will be uncompressed (also if you
  rewrite compressed clusters).
* Therefore, there's no such thing as an image with compression
  enabled. In QEMU you don't compress an image, you compress
  individual clusters of data. An image can have a mix of compressed
  and uncompressed clusters.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]