Bug 861375

Summary:	RFE: More info in qemu-img info
Product:	[Fedora] Fedora	Reporter:	Alexander Larsson <alexl>
Component:	qemu	Assignee:	Fedora Virtualization Maintainers <virt-maint>
Status:	CLOSED UPSTREAM	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	18	CC:	amit.shah, berrange, cfergeau, crobinso, dwmw2, itamar, knoel, kwolf, pbonzini, rjones, scottt.tw, stefanha, virt-maint
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	861439 920225 (view as bug list)		Environment:
Last Closed:	2012-12-15 01:25:36 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	861439, 920225

Description Alexander Larsson 2012-09-28 12:07:45 UTC

qemu-img info currently give me info like this:

image: /home/alex/.local/share/gnome-boxes/images/Fedora 16
file format: qcow2
virtual size: 11G (11794287616 bytes)
disk size: 4.5G
cluster_size: 65536

In order to figure out the "health" of an image there is some more information I would like:

in-use disk size - I.e the subset of disk size that is not marked as unused due to e.g. TRIM operations

amount of compressed clusters. I.e. "is it useful to re-compress the image".

Fragmentation estimation.

This would be useful to both sysadmins in general and for automated things like
what we want to do in gnome-boxes:
https://bugzilla.gnome.org/show_bug.cgi?id=685032

Comment 1 Richard W.M. Jones 2012-09-28 12:18:50 UTC

All sounds useful.  However these requests should probably
go upstream, along with patches!

Note upstream there is a patch floating around which adds
JSON output to qemu-img info.  This is useful because it's
a big security problem to try to parse the text output from
this command.  See:

https://lists.gnu.org/archive/html/qemu-devel/2012-09/msg00137.html

Comment 2 Daniel Berrangé 2012-09-28 15:38:08 UTC

Depending on how Boxes wants to consume this extra metadata, this may need to be done in libvirt instead, or as well. Libvirt does not actually use qemu-img info for getting file metadata, since it wants a low overhead code to extra basic properties & forking qemu-img doesn't really satisfy that.

Comment 3 Paolo Bonzini 2012-09-28 15:39:31 UTC

Fragmentation estimation and in-use space is actually quite expensive to compute---not *that* expensive but certainly worse than a fork, and worse-case O(n) in the size of the disk.

Comment 4 Stefan Hajnoczi 2012-10-23 10:17:08 UTC

Fragmentation statistics have been added to 'qemu-img check' for qcow2 and qed image files:

  commit f8111c241afa75544032dcfa23df0699c91f9866
  Author: Dong Xu Wang <wdongxu.ibm.com>
  Date:   Thu Mar 15 20:13:31 2012 +0800

      qemu-img: add image fragmentation statistics

Note this is qemu-img check and not qemu-img info, because we need to scan the image metadata (expensive on large images).

Comment 5 Kevin Wolf 2012-10-23 11:58:28 UTC

Yes, I agree that most of this should be part of 'qemu-img check' rather than 'qemu-img info'.

Fragmentation statistics are only implemented for QED as of today, qcow2 doesn't have them yet.

Comment 6 Cole Robinson 2012-12-15 01:25:36 UTC

In general I don't think RFE's make much sense in Fedora bugzilla, so I've moved this to the upstream qemu tracker:

https://bugs.launchpad.net/qemu/+bug/1090615

Alex, I couldn't find a launchpad account for you, but please follow up on that report (or qemu-devel)