On Wed, Oct 08, 2008 at 10:51:16AM -0500, Anthony Liguori wrote: > A great deal of virtualization users are doing some form of homogeneous > consolidation. If they have a good set of management tools or > sophisticated storage, then their guests will be sharing base images or > something like that. Caching in the host will result in major > performance improvements because otherwise, the same data will be > fetched multiple times. NB, this has no impact on caching of backing files - QEMU masks out the O_DIRECT flag when opening the backing file - so in a shared master image scenario, all reads for the shared file will still be cached, only write5Cs to the cow file are impacted. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list