[libvirt] ANNOUNCE: virt-mem: tools for monitoring virtual machines

Richard W.M. Jones rjones at redhat.com
Tue Jun 3 23:11:03 UTC 2008

I'm pleased to announce this very early pre-alpha release of a further
set of tools for monitoring virtual machines.

The idea is to provide simple commands which can be run outside the
virtual machine to monitor its status.  These commands don't require
you to log in to the virtual machine, or to install any software,
since they work entirely by snooping.  So they could be very useful
for analyzing guests which are stuck / unresponsive / heavily loaded.

Done so far:

  virt-uname        like uname(1), print guest's system information
  virt-dmesg        like dmesg(1), print guest's kernel messages

Coming soon:

  virt-ps           like ps(1), lists processes
  virt-free         like free(1), lists free memory and swap

If virt-ps works out, I might do a 'top'-like command, although of
course I can't call it virt-top.  I'm open to other suggestions too.

Home page: http://et.redhat.com/~rjones/virt-mem/
Source:    http://hg.et.redhat.com/virt/applications/virt-mem--devel

These require a (forthcoming) patch to libvirt to snoop on virtual
machines' memory.  At the moment you can run them by using the QEMU
memsave command to snapshot kernel memory to a file, and then run the
program on the file.  The snapshot process is described here:
Support for Xen is still under investigation, but we believe it should
be possible.


(qemu) memsave 3222274048 15728640 snap.mem

$ virt-uname -A i386 -T i386 -t ~/snap.mem
/home/rjones/snap.mem: Linux localhost.localdomain 2.6.24-0.155.rc7.git6.fc9 #1 SMP Tue Jan 15 17:52:31 EST 2008 i686 (none)


Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.

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