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Date: Tue, 15 Jun 2010 16:30:30 +0300
From: Laine Stump <laine@redhat.com>
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Subject: Re: [Qemu-devel] [Bug 524447] Re: virsh save is very slow
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> Bug description: As reported here: 
> http://www.redhat.com/archives/libvir-list/2009-December/msg00203.html 
> "virsh save" is very slow - it writes the image at around 1MB/sec on 
> my test system. (I think I saw a bug report for this issue on Fedora's 
> bugzilla, but I can't find it now...)

Here's the Fedora bug:

https://bugzilla.redhat.com/show_bug.cgi?id=599091

Note that I've already pushed a patch upstream that fixes the problem 
(reduces save time for a 512MB guest from 3:47 to 0:56), and eric Blake 
has posted a more refined patch that wastes less space by invoking dd 
twice (once for libvirt's header, and again for the image) - that hasn't 
been pushed yet, but will almost definitely supercede my patch before 
the libvirt-0.8.2 release.