[Openstack-operators] Starting large VMs takes quite long

Fri Oct 21 14:58:47 UTC 2011

"The Gluster Connector for OpenStack", it's ridiculous. Have a look at
the docs, they've done nothing concering Openstack compute.
 => http://www.gluster.com/wp-content/uploads/2011/07/Gluster-Openstack-VM-storage-v1-shehjar.pdf
They just create a normal gluster volume and store the vms on it. That
was even possible before,  I had that setup running long before.

Christian

> 2011/10/21 ghe. rivero <ghe.rivero at gmail.com>
>>
>> Hi,
>> Talking about live-migration and shared mount points, has anyone have the chance to try glusterfs connector? They claim to be able to: "Instantly boot VMs using a mountable filesystem interface – no more fetching the entire VM image before booting" (http://www.gluster.com/2011/07/27/glusters-shiny-new-connector-for-openstack/)
>> See you!
>>     Ghe Rivero
>> On Thu, Oct 20, 2011 at 4:03 PM, Diego Parrilla <diego.parrilla at stackops.com> wrote:
>>>
>>> Hi,
>>> my answers below,
>>>
>>> On Thu, Oct 20, 2011 at 3:47 PM, Boris-Michel Deschenes <boris-michel.deschenes at ubisoft.com> wrote:
>>>>
>>>> Hi guys,
>>>>
>>>>
>>>>
>>>> Just a quick note, I had this setup at some point (NFS-mounted /var/lib/nova/instances) which is essential to get live VM migrations if I’m not mistaken (live migration was working perfectly).  The problem I had with this setup was that the VM startup time was considerably slower than when the images were residing on a local disk (and I mean, even after all images are “cached”).
>>>
>>> It's true. The fastest disk and the closest to the drive the better.
>>>
>>>>
>>>>
>>>>
>>>> Basically an image will start the fastest when it is cached locally (local drive)
>>>
>>> Correct.
>>>
>>>>
>>>> Then, not quite as fast when cached but on a NFS-mounted directory
>>>
>>> Correct. It takes some time to create the local disks. It's very important to have a good connection to the shared file system (it's not mandatory to use NFS).
>>>
>>>>
>>>> Then really slowly when residing entirely on another disk and needed to be written locally to be cached.
>>>
>>> Right, it can take several minutes on a 1Gb.
>>>
>>>>
>>>>
>>>>
>>>> These are the observations I made but I realize other factors weigh in (SAS vs SATA disk, network speed, etc.)  Please advise if you get the same speed in NFS-cached vs local-cached setup as it might convince me to go back to an NFS share (also were you using SAS disks to serve the NFS?).
>>>
>>> No, the performance on local disk is much higher than running a NFS on a 1Gb. For my perspective not only live migration is a must for our customers, but also the local virtual disks must persists a catastrophic failure of a nova-compute. That's the reason why recommend 10Gb and a good performant NFS file server connected. 15K or 10K SAS is not so relevant, the bottleneck is the network (speed and latency). There are also good solutions combining 10Gb + SSD Cache disks + 7.2KRPM SAS/SATA disks.
>>> I would like to know what the people are using in real life deployments. Any more thoughts?
>>> Regards
>>> Diego
>>>
>>>>
>>>>
>>>>
>>>> Thanks
>>>>
>>>>
>>>>
>>>> De : openstack-operators-bounces at lists.openstack.org [mailto:openstack-operators-bounces at lists.openstack.org] De la part de Diego Parrilla
>>>> Envoyé : 20 octobre 2011 04:54
>>>> À : Till Mossakowski
>>>> Cc : openstack-operators at lists.openstack.org
>>>> Objet : Re: [Openstack-operators] Starting large VMs takes quite long
>>>>
>>>>
>>>>
>>>> Hi,
>>>>
>>>>
>>>>
>>>> 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 /var/lib/nova/instances
>>>>
>>>> 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.
>>>>
>>>>
>>>>
>>>> Regards
>>>>
>>>> Diego
>>>>
>>>>
>>>>
>>>> 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.!!!:
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>>>> Amtsgericht Kaiserslautern, HRB 2313
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> Diego Parrilla
>>>> CEO
>>>> www.stackops.com |  diego.parrilla at stackops.com | +34 649 94 43 29 | skype:diegoparrilla
>>>>
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>>>>
>>>>
>>>>
>>>>
>>>
>>> --
>>> Diego Parrilla
>>> CEO
>>> www.stackops.com |  diego.parrilla at stackops.com | +34 649 94 43 29 | skype:diegoparrilla
>>>
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>>
>>
>>
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