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[Qemu-devel] [PATCH 02/10] qemu-img: Explain how rebase operation can be
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 02/10] qemu-img: Explain how rebase operation can be used to perform a 'diff' operation. |
Date: |
Fri, 25 May 2012 19:38:46 +0200 |
From: "Richard W.M. Jones" <address@hidden>
Signed-off-by: Richard W.M. Jones <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
qemu-img.texi | 18 ++++++++++++++++++
1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/qemu-img.texi b/qemu-img.texi
index b2ca3a5..6fc3c28 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -159,6 +159,24 @@ It can be used without an accessible old backing file,
i.e. you can use it to
fix an image whose backing file has already been moved/renamed.
@end table
+You can use @code{rebase} to perform a ``diff'' operation on two
+disk images. This can be useful when you have copied or cloned
+a guest, and you want to get back to a thin image on top of a
+template or base image.
+
+Say that @code{base.img} has been cloned as @code{modified.img} by
+copying it, and that the @code{modified.img} guest has run so there
+are now some changes compared to @code{base.img}. To construct a thin
+image called @code{diff.qcow2} that contains just the differences, do:
+
address@hidden
+qemu-img create -f qcow2 -b modified.img diff.qcow2
+qemu-img rebase -b base.img diff.qcow2
address@hidden example
+
+At this point, @code{modified.img} can be discarded, since
address@hidden + diff.qcow2} contains the same information.
+
@item resize @var{filename} [+ | address@hidden
Change the disk image as if it had been created with @var{size}.
--
1.7.6.5
- [Qemu-devel] [PULL 00/10] Block patches for 1.1, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 01/10] qcow2: don't leak buffer for unexpected qcow_version in header, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 02/10] qemu-img: Explain how rebase operation can be used to perform a 'diff' operation.,
Kevin Wolf <=
- [Qemu-devel] [PATCH 03/10] sheepdog: mark image as snapshot when tag is specified, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 04/10] sheepdog: return -errno on error, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 06/10] qcow2: Check qcow2_alloc_clusters_at() return value, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 05/10] sheepdog: use heap instead of stack for BDRVSheepdogState, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 09/10] fdc: fix media detection, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 08/10] fdc: floppy drive should be visible after start without media, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 07/10] qemu-iotests: mark 035 qcow2-only, Kevin Wolf, 2012/05/25
- [Qemu-devel] [PATCH 10/10] fdc-test: introduced qtest no_media_on_start and cmos qtest for floppy, Kevin Wolf, 2012/05/25
- Re: [Qemu-devel] [PULL 00/10] Block patches for 1.1, Anthony Liguori, 2012/05/29