Re: [Libguestfs] [PATCH v4 0/3] v2v: Add -o rhv-upload output mode.
On Wed, Mar 14, 2018 at 09:07:31PM +0000, Nir Soffer wrote:
On Wed, Mar 14, 2018 at 9:04 PM Richard W.M. Jones
<rjones(a)redhat.com>
wrote:
> FWIW NBD allows you to flush ranges or flush the whole disk, in case
> that matters (your proposal only allows you to flush the whole disk).
>
What is the use case for flushing ranges?
The use case is that (eg) your editor inside a VM calls fdatasync.
This could be implemented by the hypervisor either by flushing the
entire virtual disk, or by writing just the blocks associated with the
file being editing and setting the FUA flag on those writes. The
first one flushes out far more data than is really necessary to
satisfy the request.
I don't think any of this applies to oVirt imageio, so we don't need
it to be implemented.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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