[Qemu-discuss] Snapshot question

[Angus Gardner]

Hi qemu-discuss,

 

I have a quick question regarding snapshot mode.

 

I have been able to run qemu in snapshot mode and trace file operations.  The ‘C:’ disk is opened read only and all new writes to the disk image go to a second image file, as per the documentation.  EG:

 

Opening the disk image RO:

open("winxp.qcow", O_RDONLY|O_NONBLOCK|O_LARGEFILE) = 10

 

Opening the install cdrom image RO:

open("WinXP_Install.iso", O_RDONLY|O_NONBLOCK|O_LARGEFILE) = 6

 

A second disk image file is opened (RW):

open("/tmp/vl.hIndzH", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0600) = 6

 

Qemu then unlinks the new file

unlink("/tmp/vl.hIndzH")

but keeps reading and writing to it until the process is shut down, at which time it is lost.

 

My question is:

Is there a way to create this temporary disk image file in a user definable place and have it persist after shutdown?

 

This would be really useful in creating multiple VM’s which use less disk space and in creating a VM which can be used for a honeypot.

 

Thanks,

angus