Re: [Qemu-devel] [PATCH 2/2] drive_open: Add invalidate option for block devices

[Juan Quintela]

Kevin Wolf <address@hidden> wrote:
> Am 09.11.2011 20:16, schrieb Juan Quintela:
>> Linux allows to invalidate block devices.  This is needed for the incoming
>> migration part.
>> 
>> Signed-off-by: Juan Quintela <address@hidden>
>
> I think Christoph said that this ioctl kills ramdisks? Or was that
> something different?

On patch 0/2 I said that I was not proposing this.  That this "kind" of
fixed the problem for iscsi and linux, but that it is not "reliable".

Patch 2/2 was to start discussion, and to show the problem we had to
fix, not a "solution".

As said during the discussion:
- clustered filesystems: they are good
- non-coherentent shared storage (NFS, iSCSI, ...): needs cache=none,
  anything else is insane
- formats (qcow2): needs reopen, or at least reload metadata.

And the discussion is how to go from here.

Later, Juan.