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Date: Wed, 05 Mar 2008 15:55:17 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Signal handling and qcow2 image corruption
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To: qemu-devel@nongnu.org

David Barrett wrote:
> I'm tracking down a image corruption issue and I'm curious if you can 
> answer the following:
>
> 1) Is there any difference between sending a "TERM" signal to the QEMU 
> process and typing "quit" at the monitor?

Yes.  Since QEMU is single threaded, when you issue a quit, you know you 
aren't in the middle of writing qcow2 meta data to disk.

> 2) Will sending TERM corrupt the 'gcow2' image (in ways other than 
> normal guest OS dirty shutdown)?

Possibly, yes.

> 3) Assuming I always start QEMU using "-loadvm", is there any risk in 
> using 'kill' to send SIGTERM to the QMEU process when done?

Yes.  If you want to SIGTERM QEMU, the safest thing to do is use -snapshot.

Regards,

Anthony Liguori