Re: [libvirt] [PATCH 2/2] Adjust block size used by dd to speed QEMU domain save operations.

On Thu, Jun 03, 2010 at 11:57:33PM -0400, Laine Stump wrote: > See https://bugzilla.redhat.com/show_bug.cgi?id=599091 > > Saving a paused 512MB domain took 3m47s with the old block size of 512 > bytes. Changing the block size to 1024*1024 decreased the time to 56 > seconds. (Doubling again to 2048*1024 yielded 0 improvement; lowering > to 512k increased the save time to 1m10s, about 20%) Surely we should have gone for 1024*1024 in this case ? NB, since our XML header gets rounded up to a multiple of the block size, smaller is better, because we're filling the disk with zeros here :-)