Re: [Qemu-devel] [RFC] Disk integrity in QEMU

[Rik van Riel]

Anthony Liguori wrote:

> When cache=on, read requests may not actually go to the disk.  If a 
> previous read request (by some application on the system) has read the 
> same data, then it becomes a simple memcpy().  Also, the host IO 
> scheduler may do read ahead which means that the data may be available 
> from that. 

This can be as much of a data integrity problem as
asynchronous writes, if various qemu/kvm guests are
accessing the same disk image with a cluster filesystem
like GFS.

--
All rights reversed.