FWN/Beats/Virtualization

Virtualization

In this section, we cover discussion on the @et-mgmnt-tools-list, @fedora-xen-list, @libvirt-list and @ovirt-devel-list of Fedora virtualization technologies.

Contributing Writer: Dale Bewley

Enterprise Management Tools List

This section contains the discussion happening on the et-mgmt-tools list

Fedora Xen List

This section contains the discussion happening on the fedora-xen list.

Support for F10 domU on RHEL5.2 dom0

Jon Stanley noticed[1] that a RHEL 5.2 dom0 was unable to install a current Fedora 10 Rawhide domU. Mark McLoughlin explained[2] that the "older virt-install doesn't know to look in the 'images-xen' stanza in the '.treeinfo' file to determine which images to use". Patches are being backported to RHEL 5.3 for this[3]. A further issue[4] is a lack of bzimage support in the libxc of RHEL.

[1] https://www.redhat.com/archives/fedora-xen/2008-October/msg00002.html

[2] https://www.redhat.com/archives/fedora-xen/2008-October/msg00003.html

[3] https://bugzilla.redhat.com/460585

[4] https://bugzilla.redhat.com/457199

Michael Young asked[5] about a timeline for these patches and expressed concern that there could be "a period of time where there won't be any supported Redhat or Fedora platform to run Xen guests, and of course the lack of current support in RHEL is reducing the testing that Fedora 10 xen is getting."

[5] https://www.redhat.com/archives/fedora-xen/2008-October/msg00006.html

Libvirt List

This section contains the discussion happening on the libvir-list.

KVM Domain Migration Not Yet Supported

Kenneth Nagin noticed[1] a problem migrating a KVM guest. Daniel P. Berrange said[2] that's because it's not yet supported. "Currently KVM's private fork of QEMU has some migration support, but this is not written in a suitable way for " libvirt "to use - it blocks the QEMU monitor on startup. Upstream QEMU is getting better migration support and once that's done we can support it in libvirt."

[1] https://www.redhat.com/archives/libvir-list/2008-October/msg00147.html

[2] https://www.redhat.com/archives/libvir-list/2008-October/msg00148.html

Disable QEMU Drive Cacheing

Daniel P. Berrange posted[1] a patch with the following explaination.

QEMU defaults to allowing the host OS to cache all disk I/O. This has a couple of problems

• It is a waste of memory because the guest already caches I/O ops
• It is unsafe on host OS crash - all unflushed guest I/O will be lost, and there's no ordering guarantees, so metadata updates could be flushed to disk, while the journal updates were not. Say goodbye to your filesystem.
• It makes benchmarking more or less impossible / worthless because what the benchmark things are disk writes just sit around in memory so guest disk performance appears to exceed host diskperformance.

This patch disables caching on all QEMU guests. NB, Xen has long done this for both PV & HVM guests - QEMU only gained this ability when -drive was introduced, and sadly kept the default to unsafe cache=on settings.

[1] https://www.redhat.com/archives/libvir-list/2008-October/msg00180.html

NSIS Windows Installer in Nightly Builds

Richard W.M. Jones added[1] NSIS[2] support to generate a Windows installer in the nightly build. Richard also recently blogged[3] on the subject on MinGW and NSIS.

[1] https://www.redhat.com/archives/libvir-list/2008-October/msg00191.html

[2] http://nsis.sourceforge.net/

[3] http://camltastic.blogspot.com/2008/10/mingw-compile-software-for-windows.html

In reply to another thread[4] Daniel P. Berrange explained support is targeted for "client-mode only. ie, allow use of libvirt clients to connect to remote Linux hosts running libvirtd", and that there is no emminent Hyper-V or VMWare support.

[4] https://www.redhat.com/archives/libvir-list/2008-October/msg00304.html

Domain Events API Progress

Ben Guthro posted[1] patches to implement domain state transition events which were previously discussed[2].

[1] https://www.redhat.com/archives/libvir-list/2008-October/msg00245.html

[2] http://www.redhat.com/archives/libvir-list/2008-September/msg00321.html

oVirt Devel List

This section contains the discussion happening on the ovirt-devel list.

oVirt Qpid API

Ian Main continues to work[1] on a qpid API for oVirt which leverages the device enumeration[2] and qpid support[3] in libvirt. Ian extended the oVirt API to include network configuration information. Ian also posted[4] a demo script.

[1] https://www.redhat.com/archives/ovirt-devel/2008-October/msg00101.html

[2] https://fedoraproject.org/wiki/FWN/Issue146#Host_Device_Enumeration_API

[3] https://fedoraproject.org/wiki/FWN/Issue146#QPID_Modeling_Framework_and_libvirt-qpid

[4] https://www.redhat.com/archives/ovirt-devel/2008-October/msg00150.html