[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 00/14] block (mostly qcow2) changes (v6)

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH 00/14] block (mostly qcow2) changes (v6)
Date: Tue, 24 Mar 2009 13:44:49 +0200
User-agent: Thunderbird (X11/20090320)

Gleb Natapov wrote:
On Tue, Mar 17, 2009 at 10:40:38PM +0200, Uri Lublin wrote:
Changes from v5:
   Patchset includes newly introduced qcow2 extensions.
Usage of such qcow2 extensions for keeping both backing format and highest-allocated-offset.
   No scanning of qcow2 images upon open.
highest-allocated-offset is written to a disk only if block device was closed
properly, so this value can't actually be trusted to be accurate. How
important is to maintain it accurate? If it is important it should be
saved on disk as part of a metadata update and if it is not it can be
updated on a first guest write that requires new block allocation.

Good catch.

I suggest a different approach. Have a notification that triggers when a write past a certain offset occurs:

   (qemu) block_watermark_notify ide0-0 123564435343
   ... time passes ...
   (qemu) #block watermark exceeded: ide0-0 127454566544

This is in addition to pausing the VM on write error.

Do not meddle in the internals of kernels, for they are subtle and quick to 

reply via email to

[Prev in Thread] Current Thread [Next in Thread]