|
From: | Eric Blake |
Subject: | Re: [Qemu-block] [Qemu-devel] [PATCH] qemu-img: return allocated size for block device with qcow2 format |
Date: | Wed, 2 May 2018 10:19:03 -0500 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 05/02/2018 10:13 AM, Max Reitz wrote:
We also recently added 'qemu-img measure', which DOES report how many clusters are in use. Is any of that reusable here?It only tells you that information for a hypothetical new image, though, doesn't it?
It has two uses: with just a size, estimate the overhead needed to create a file with the given format and exposing the given size to the guest (both sparse and fully allocated sizes are estimated); and with a pre-existing image, compute the exact overhead needed for 'qemu-img convert' to create a new image with the given format and the same guest-visible contents. The latter use, where it uses an existing guest image as the starting point to measure, indeed only tells you what a hypothetical new image will occupy (the used cluster count, not the wr_highest_offset count) - but isn't that what you want?
-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
[Prev in Thread] | Current Thread | [Next in Thread] |