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+++ This bug was initially created as a clone of Bug #1113020 +++

Description of problem:
virt-sparsify requires a large amount of temporary space in order to sparsify an image. On oVirt nodes we may not have enough temporary local space and we don't want to pollute the hosts with potentially sensible data (even though the temporary layer would most likely just contain zeroes).

It should be possible to specify a temporary oVirt volume (residing on the storage domains) that can be used for processing the image.
The volume can either be a single file or a single block device (logical volume).

dev-ack, but I believe it's too late for RHEL 6.6 now.

We also need the --tmp prebuilt: support.

The two commit which implement this are:

9b47a53a4b sparsify: Add --tmp prebuilt:file option.
870c17e99a sparsify: Add --tmp option to allow specifying temp directory or

Federico has requested that we try to get this into RHEL 6.6,
to support the next release of oVirt.

Version:
Host: RHEL6.6(2.6.32-498.el6.x86_64)
libguestfs: libguestfs-1.20.11-10.el6.x86_64

Steps:
1. virt-sparify -v $image1 image2 --tmp /nfs
2. ll /nfs
-rw-------. 1 root root 4651810816 Sep  3 15:55 sparsify78ca25.qcow2

Result:

We can verify this bug as above.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1458.html