Re: [PATCH v4 24/30] qcow2: Clear the L2 bitmap when allocating a compressed cluster

[Alberto Garcia]

On Fri 24 Apr 2020 08:15:04 PM CEST, Vladimir Sementsov-Ogievskiy 
<address@hidden> wrote:
> AFAIK, now compressed clusters can't be used in scenarios with guest,
> as qcow2 driver doesn't support rewriting them.

You can write to those images just fine, it's just not efficient because
you have to COW the compressed clusters.

> Or am I wrong? And we normally don't combine normal and compressed
> clusters together in one image.

As soon as you start writing to an image with compressed clusters you'll
have a combination of both.

But it's true that you don't have an image with compressed clusters if
what you're looking for is performance. So I wouldn't add support for
this if it complicates things too much.

Berto