Re: [Qemu-devel] The image size of instance VM keeps growing

[Charles . Tsai-蔡清海-研究發展部]

Stefan,

Thank you for information. We will try to isolate the issue here and give you 
an update.


-----Original Message-----
From: Stefan Hajnoczi [mailto:address@hidden 
Sent: Monday, May 21, 2012 9:24 PM
To: Charles.Tsai-蔡清海-研究發展部
Cc: address@hidden; Jonah.Wu-吳君勉-研究發展部
Subject: Re: [Qemu-devel] The image size of instance VM keeps growing

On Mon, May 21, 2012 at 10:08 AM, Charles.Tsai-蔡清海-研究發展部
<address@hidden> wrote:
> We can run a tool to see if there is any active I/O or not. Does the image 
> size shrink back if an I/O activity stops?
> What we found here is that the image size kept growing. If this problem 
> persists, it could eat up the entire disk space.

It's possible for an image to grow larger than its backing file due to the 
layout and metadata of qcow2 (or any image file format).  But this overhead 
should be fixed to maximum 1 MB, maybe (assuming you are not using qcow2 
snapshots where the file can grow arbitrarily).

If the image file is growing endlessly then there is a problem :).
The starting point is figuring out which I/O request causes this to happen so 
it can be reproduced and debugged.  Can you isolate the problem to a few steps 
that can be reproduced?

Stefan