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

Re: [libvirt] qemu and <transient/> disks



On Mon, Jul 23, 2012 at 10:28:57AM +0100, Daniel P. Berrange wrote:
> I agree with the quoted text that libvirt should define a
> directory to use for the transient disks under /var/lib/libvirt/images
> perhaps, and just use 'qemu-img create' to create that, and the
> unlink it once QEMU has started up, so we can auto-cleanup
> on QEMU shutdown.

One issue here is that 'qemu-img create' is slow.  0.4 seconds to
create a qcow2 file backing another file (ie. per readonly disk, and
programs like virt-df may open dozens of readonly disks).

I looked at the strace output and it seems the slowness is just
overhead from the machinery of qemu's coroutines, and not connected
with writing the qcow2 file, which is presumably why the qemu
snapshot=on option is not noticably slow.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw


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