Comment 2 for bug 568445

I fail to see how not using a cache provides any less data integrity than using one. The default caching method, as you quote, is writethrough which according to the manpage states:

           By default, writethrough caching is used for all block device.
           This means that the host page cache will be used to read and write
           data but write notification will be sent to the guest only when the
           data has been reported as written by the storage subsystem.

The same should be true with no caching, correct?

The fact that the default writethrough caching results in slower VM disk I/O and a subsequently higher host load is fairly obvious. The links provided in the original report show that LVM backed stores using cache='none' perform significantly better than the default.