[Openstack-operators] Starting large VMs takes quite long

Diego Parrilla diego.parrilla at stackops.com
Thu Oct 20 08:53:40 UTC 2011


my answers below.

On Wed, Oct 19, 2011 at 8:12 PM, Till Mossakowski
<Till.Mossakowski at dfki.de>wrote:

> Hi,
>  my answers below,
> many thanks for your quick answer.
>     I have set up openstack using stackops.
>> Good choice ;-)
> Yes, the stackops GUI is very nice. However, stackops is based on cactus,
> right? Is there a way of using diablo with stackops? Perhaps it is possible
> to upgrade the Ubuntu lucid distro that is coming with stackops to natty or
> oneiric and then upgrade to diablo using the source
> ppa:openstack-release/2011.3 for openstack?

Yes, the 0.3 version with Diablo release is coming. We detected some QA
issues. But things are working much better now.

>  5GB image it's not too big... we use NFS to share instances among nodes
>> to help with the live migration and performance it's acceptable. How
>> much is 'quite a while' in seconds?
> between half a minute and a minute (I haven't taken the exact time...).
> This is too long for our users.

If the virtual disks are cached, launching a 40GB virtual machine takes less
than 5 seconds in our test platform (IBM x3550M3 Dual Xeon 5620 64GB with
NFS as shared storage on 1Gb)

>  If you share the /var/lib/nova/instances with NFS, during the 'launch'
>> process the base virtual image is copied to '_base'. Depending on the
>> size of this file it will take longer. Once it's copied next time you
>> use this image it should go much faster.
>> Note: I have tested right now with a 1Gb launching a >25GB Windows VM
>> and it took 3-4 minutes the first time. New Windows images, it took only
>> a few seconds.
> This is interesting. Is there a way of telling the scheduler to prefer a
> compute node that already has copied the needed image?

Try this:

1) Configure the compute nodes to use a shared directory with NFS on
2) Launch ALL the virtual disks you need at runtime. It will take a while
the first time.
3) Virtual disks are now cached in /var/lib/nova/instances/_base
4) Try to launch now the virtual disks again. They should start very fast.

If you need some kind of assistance, please let me know.


> Best, Till
> --
> Prof. Dr. Till Mossakowski  Cartesium, room 2.51 Phone +49-421-218-64226
> DFKI GmbH Bremen                             Fax +49-421-218-9864226
> Safe & Secure Cognitive Systems             Till.Mossakowski at dfki.de
> Enrique-Schmidt-Str. 5, D-28359 Bremen   http://www.dfki.de/sks/till
> Deutsches Forschungszentrum fuer Kuenstliche Intelligenz GmbH
> principal office, *not* the address for mail etc.!!!:
> Trippstadter Str. 122, D-67663 Kaiserslautern
> management board: Prof. Wolfgang Wahlster (chair), Dr. Walter Olthoff
> supervisory board: Prof. Hans A. Aukes (chair)
> Amtsgericht Kaiserslautern, HRB 2313

Diego Parrilla
*www.stackops.com | * diego.parrilla at stackops.com** | +34 649 94 43 29 |
* <http://www.stackops.com/>


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