openstack team mailing list archive

["Chris Bartels" <chris@xxxxxxxxxxxxxxxxxxxxxx>]

Thanks. This approach looks promising.

 

From: Alex Glikson [mailto:GLIKSON@xxxxxxxxxx] 
Sent: Saturday, June 01, 2013 2:18 AM
To: openstack@xxxxxxxxxxxxxxxxxxx; chris@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [Openstack] VM disk affinity during live migration

 

Right. A slightly different approach (requiring admin effort) would be to
define two host aggregates -- one reporting SSD as one of the capabilities
of its hosts, and another one reporting SAS. Then the admin can attach the
corresponding capability as a an extra spec of an instance flavor, and use
Filter Scheduler with AggregateInstanceExtraSpecsFilter to make sure
instances would not be placed on a hosts which belong to a wrong aggregate.
All this can be done already (see
http://docs.openstack.org/trunk/openstack-compute/admin/content/host-aggrega
tes.html). The missing piece (which is, I believe, going to be resolved in
Havana) would be to prevent admin from live-migrating an instance to a wrong
location manually (but this wouldn't be an issue if the admin live-migrates
without explicitly specifying destination, as Jay pointed out). 

Regards, 
Alex 




From:        Lau Jay <jay.lau.513@xxxxxxxxx> 
To:        chris@xxxxxxxxxxxxxxxxxxxxxx, 
Cc:        Alex Glikson/Haifa/IBM@IBMIL, openstack@xxxxxxxxxxxxxxxxxxx 
Date:        01/06/2013 07:39 AM 
Subject:        Re: [Openstack] VM disk affinity during live migration 

  _____  




Hi Chris, 

I think that you are using live migration without specifying target host,
right? OpenStack cannot handle your case for now, but it has very flexible
framework to enable you DIY your migration logic.

1) Make sure SSD or SAS can be reported by nova compute, you might want to
update nova compute driver to report those metrics? 
2) Add a new scheduler filter to do your logic checking for SSD and SAS.

Thanks,

Jay



2013/6/1 Chris Bartels <chris@xxxxxxxxxxxxxxxxxxxxxx> 
Thanks for your reply. 

  

Your reply implies that its possible to ensure that the disks stay on the
right target manually. What would you have to do to make sure this happened?


  

The SAS space is 228GB & the SSD space is only 64GB. 

  

So the SAS disk image wouldn't fit on the SSD, but the SSD image would fit
on the SAS, so the migration system I imagine wouldn't be able to screw it
up since it would have to keep the large SAS image on the SAS target, and
would then only be able to place the smaller SSD image on the SSD. 

  

But you say it's a work in progress so that could mean anything could
happen. 

  

What does the actual process look like when I would migrate a VM from one
server to another? What exactly would I have to do to make sure it went
right? 

  

Thanks. 

  

From: Alex Glikson [mailto: <mailto:GLIKSON@xxxxxxxxxx> GLIKSON@xxxxxxxxxx] 
Sent: Friday, May 31, 2013 7:34 AM
To:  <mailto:chris@xxxxxxxxxxxxxxxxxxxxxx> chris@xxxxxxxxxxxxxxxxxxxxxx
Cc:  <mailto:openstack@xxxxxxxxxxxxxxxxxxx> openstack@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Openstack] VM disk affinity during live migration 

  

There is an ongoing work to refactor live migration code, including use of
scheduler to find/validate placement. At the moment the admin would need to
make sure he/she is doing the right thing. 

Regards, 
Alex 



From:        "Chris Bartels" < <mailto:chris@xxxxxxxxxxxxxxxxxxxxxx>
chris@xxxxxxxxxxxxxxxxxxxxxx> 
To:        < <mailto:openstack@xxxxxxxxxxxxxxxxxxx>
openstack@xxxxxxxxxxxxxxxxxxx>, 
Date:        31/05/2013 02:12 PM 
Subject:        [Openstack] VM disk affinity during live migration 
Sent by:        "Openstack" <
<mailto:openstack-bounces+glikson=il.ibm.com@xxxxxxxxxxxxxxxxxxx>
openstack-bounces+glikson=il.ibm.com@xxxxxxxxxxxxxxxxxxx> 

  _____  




Hi, 
  
Please forgive me if I've asked already here on the list- I didn't get a
reply & I really need an answer, so I'm asking again in simpler terms this
time. 
  
If I have a cluster of servers, each with spindle drives & SSDs, how can I
be sure VM disks which reside on spindle drives migrate to spindle drives &
those which reside on SSDs stay on SSDs as they migrate between servers? 
  
Thanks, 
Chris_______________________________________________
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