Re: [Qemu-devel] [RFC] block-trace Low Level Command Supporting Disk Introspection

[Wolfgang Richter]

On Tue, May 14, 2013 at 4:40 AM, Stefan Hajnoczi <address@hidden> wrote:

QEMU is accumulating many different approaches to snapshots and
mirroring.  They all have their pros and cons so it's not possible to
support only one approach for all use cases.

The suggested approach is writing a BlockDriver which mirrors I/O to two
BlockDriverStates.  There has been discussion around breaking
BlockDriver into smaller interfaces, including a BlockFilter for
intercepting I/O, but this has not been implemented.  blkverify is an
example of a BlockDriver that manages two child BlockDriverStates and
may be a good starting point.

BlockFilter sounds interesting.  The main reason I proposed 'block-trace'

is because that is almost identical to what I currently have implemented

with the tracing framework---I just didn't have a nice QMP command.

--
Wolf