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=== oVirt Devel List ===
This section contains the discussion happening on the
[ ovirt-devel list].
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Revision as of 05:53, 27 July 2009


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

Contributing Writer: Dale Bewley

Fedora Virtualization List

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

New Release libguestfs 1.0.64

Richard Jones announced [1] the release of Package-x-generic-16.pnglibguestfs 1.0.64.

New Features:

  • New tool: virt-cat. This tool lets you copy out files from a guest.[2]
  • Added libguestfs-test-tool which is a tool you can use to diagnose qemu / kernel booting problems, and also make bug reports more useful.
  • [Sys::Guestfs::Lib] split $os->{version} into $os->{major_version} and $os->{minor_version}. Add feature tags. (Matt Booth).
  • Allow TMPDIR to be used to override the location of temporary files.
  • Implement the guestfs_read_file call.
  • New calls guestfs_mkmountpoint and guestfs_rmmountpoint to allow some specialized read-only or nested filesystems to be mounted, particularly for examining live CDs.[3]
  • New call guestfs_mountpoints to return a hash of device -> mountpoint.
  • Many documentation fixes, including an "API Overview"[4] section which will help developers navigate parts of the now very large libguestfs API.
  • Add ~ and ~username expansion in guestfish (RHBZ #511372).
  • Add kernel modules for reading DOS filesystems (Guido Gunther).
  • Add i18n support for Perl strings.

Swap Use in Guests

Rich Mahn asked[1] "How big should the swap parititons be on virtual machines under qemu, qemu/kvm?" "It seems to me that if the VM actually needs swap space, it would be more efficient to allocate more virual[sic] memory to it."

Richard Jones found[2] this to be an interesting question, but argued "One place I think you're wrong is the assumption that adding more memory to a VM is better than having the VM use a swap disk. The reason would be that the VM's memory manager will assume that the [from its point of view] physical memory will be much faster than swap, and so will arrange memory vs swap use accordingly. But this assumption isn't true, this so-called physical memory is really just as slow as swap!" Richared pointed out Kernel Shared Memory[3] further complicates things.

Dor Laor added[4] "Guest swapping is a reasonable scenario that should be allowed and supported." On the question of oversubscribing host memory to guests, Dor said "You can overcommit VM memory and it might be good if you have many VMs that have low memory foot print. If it is not the case, you better not do it."

Clustering libvirt Hosts

Gianluca Cecchi asked[1] "is there any pointer about how to set up a cluster of Qemu/KVM hosts?" "What are the uuid tags into the xml for? Do they have to be identical for clusters or do they have to be absolutely different for a sort of "identification" of host (as the term seems to suggest)?"

Richard Jones pointed out oVirt[2] "which is an open source management tool designed precisely for looking after networks of virt hosts. It is based on libvirt, and they have looked at and solved many of the issues you raise."

Guido Günther answered[3] "In principle they don't have to be the same across hosts since you can identify the network by name and the volumes by their path but I prefer to keep them in sync (using shared nfs in my case)."

Virtualization Tools List

This section contains the discussion happening on the virt-tools-list list.

Virtual Machine Cloning

Cole Robinson with some UI designs from Jeremy Perry patched[1] Package-x-generic-16.pngvirt-manager to include a virtual machine cloning wizard.

Virt Manager UI Rework

Cole Robinson has "been reworking the main manager view in virt-manager" and asked[1] for comments.

In another UI tweak, Cole created[2] a system tray icon that "can be used to quit the app, or start, stop, pause, or open a VM."

Support for Processor Affinity

Michal Novotny submitted[1] a patch to virt-manager which enables pinning a guest to a select physical CPU.

Virt What?

Another week, another release[1] from Richard Jones.

virt-what[2] "is a collection of code snippets to allow you to determine what sort of virtualization you are running inside."

"The new version can tell the difference between QEMU and KVM, and can tell if you are running inside a Xen fullvirt guest."

Libvirt List

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