[Pkg-libvirt-maintainers] Bug#692041: libvirt-bin: vol-clone painfully slow (cloning ext4 LVM Volumes encrypted with LUKS)

[defa]

Package: libvirt-bin
Version: 0.8.3-5+squeeze2
Severity: normal


I have a LVM volume group used as storage pool by libvirt. The Volume
group is crypted using LUKS. All Volumes wihtin that group contain ext4
filesystems. When I clone such an LVM Volume, vol-clone will work, but
only allocates with approx. 1MB/s. To rule out any hardware problems I
also validated my resulst using dd which is able to copy at about
25MB/s.
While looking for a solution I found a bug report for Fedora, which
describes the same symptoms:

https://bugzilla.redhat.com/show_bug.cgi?id=582356

It also contains a link to a patch: 

http://libvirt.org/git/?p=libvirt.git;a=commit;h=e3c36a2575bc88a16d776693dc39ea01c780b406

I am not sure whether it's the same problem, but it feels like it is.

-- System Information:
Debian Release: 6.0.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-5-amd64 (SMP w/24 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libvirt-bin depends on:
ii  adduser            3.112+nmu2            add and remove users and groups
ii  libavahi-client3   0.6.27-2+squeeze1     Avahi client library
ii  libavahi-common3   0.6.27-2+squeeze1     Avahi common library
ii  libblkid1          2.17.2-9              block device id library
ii  libc6              2.11.3-4              Embedded GNU C Library: Shared lib
ii  libcap-ng0         0.6.4-1               An alternate posix capabilities li
ii  libdevmapper1.02.1 2:1.02.48-5           The Linux Kernel Device Mapper use
ii  libgcrypt11        1.4.5-2               LGPL Crypto library - runtime libr
ii  libgnutls26        2.8.6-1+squeeze2      the GNU TLS library - runtime libr
ii  libnl1             1.1-6                 library for dealing with netlink s
ii  libparted0debian1  2.3-5                 The GNU Parted disk partitioning s
ii  libpciaccess0      0.12.0-1              Generic PCI access library for X
ii  libreadline6       6.1-3                 GNU readline and history libraries
ii  libsasl2-2         2.1.23.dfsg1-7        Cyrus SASL - authentication abstra
ii  libudev0           164-3                 libudev shared library
ii  libuuid1           2.17.2-9              Universally Unique ID library
ii  libvirt0           0.8.3-5+squeeze2      library for interfacing with diffe
ii  libxenstore3.0     4.0.1-5.4             Xenstore communications library fo
ii  libxml2            2.7.8.dfsg-2+squeeze5 GNOME XML library
ii  logrotate          3.7.8-6               Log rotation utility

Versions of packages libvirt-bin recommends:
ii  bridge-utils      1.4-5                  Utilities for configuring the Linu
pn  dnsmasq-base      <none>                 (no description available)
pn  ebtables          <none>                 (no description available)
ii  gawk              1:3.1.7.dfsg-5         GNU awk, a pattern scanning and pr
ii  iptables          1.4.8-3                administration tools for packet fi
pn  libxml2-utils     <none>                 (no description available)
ii  netcat-openbsd    1.89-4                 TCP/IP swiss army knife
ii  qemu-kvm          0.12.5+dfsg-5+squeeze9 Full virtualization on x86 hardwar

Versions of packages libvirt-bin suggests:
pn  policykit-1                   <none>     (no description available)

-- Configuration Files:
/etc/libvirt/qemu.conf changed:
vnc_listen = "0.0.0.0"


-- no debconf information