Implement Availability Zone scheduler

Asked by Sateesh Bodla

Hi,

I want to know how to configure the scheduler to use Availability Zone scheduling algorithm. I am using this in Essex version. In diablo I have seen that there is zone.py which has ZoneScheduler implementation. So I can use --scheduler_compute_driver as nova.scheduler.zone.ZoneScheduler. But in Essex this has been moved to filters. So can any one tell me on how to use this in Essex.

Also, please provide the pointers on the document for Scheduler work flow.

Thanks in advance,
Sateesh B.

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Vish Ishaya
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Vish Ishaya (vishvananda) said :
#1

The availability zone scheduler is enabled by default, so you should be able to specify an availability zone and have it work. If you want to force all instances into a particular zone if the user does not specify one you can use the config option:

default_schedule_zone=xxxxx

where xxxxx is the name of the zone you would like them to go into. Keep in mind that zones are currently a config option set when you start nova-compute via:

node_availability_zone=yyyyy

Where yyyyy is the name of the zone that the host should be a part of.

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Sateesh Bodla (sateesh-bodla) said :
#2

Thanks Vish for your reply.

I have seen that the zone-add is been removed from Essex version. Can you please let me know on how to add a zone to parent in Essex version and check whether the connection is active or not. In diablo we can see that using zone-list whether it is active or not.

Also you have mentioned the config node_availability_zone=yyyyy, is this to be mentioned in child node?

Thanks,
Sateesh B.

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John Garbutt (johngarbutt) said :
#3

Note:
Cells/Zones is admin visible
"Availability Zone" is user visible

Availability Zone is configured using the flags in the nova.conf file:
node_availability_zone="nova"

See:
http://wiki.openstack.org/NovaConfigOptions

Zones are being replaced by cells in Folsom:
http://comstud.com/FolsomCells.pdf
http://etherpad.openstack.org/FolsomComputeCells

I don't think Essex has any support for Zones, the code was removed.

Hopefully that helps.

Thanks,
John

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Sateesh Bodla (sateesh-bodla) said :
#4

Hi john,

As you said that "I don't think Essex has any support for Zones, the code was removed." which conflicts with the vish statement "The availability zone scheduler is enabled by default".

Also look at the Question https://answers.launchpad.net/nova/+question/185840 which specifies that Alejandro Comisario has set up the multi zone set up.

Please clarify.

Thanks,
Sateesh B.

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John Garbutt (johngarbutt) said :
#5

Vish is correct, it filters by "Availability Zone". This is setup using the settings in the nova.conf file.

This has nothing to do with the old "add zone" call. That was the "Zones" feature that has been removed, and it will be called "Cells" when it (hopefully) gets added back into Folsom.

Sorry for the confusion, the terms are confusing, hence the rename to "Cells".

In this question:
https://answers.launchpad.net/nova/+question/185840
They used an early build of Essex when the old Zone stuff was still in the code base. It has since been removed, so it is not in the final release of Essex.

I hope that makes more sense.

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Sateesh Bodla (sateesh-bodla) said :
#6

Thanks John for the reply.

So, there is no Zone support in the final version of Essex. Is there any way to acheive that.

If it supports the Zone, can you please tell the setup on how to add child zones to the parents in configuration.

Thanks,
Sateesh B.

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John Garbutt (johngarbutt) said :
#7

As far as I know, there is no Zones support in the final version of Essex.

But you can still expose the concept of "Availability Zone" to your users by setting up the nova.conf on your compute nodes with the appropriate values.

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Best Vish Ishaya (vishvananda) said :
#8

Zones were not working well and were removed in essex. They will return in Folsom in a much more robust manner. To minimize confusion with availability zones they will be called 'cells'.

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Sateesh Bodla (sateesh-bodla) said :
#9

Thanks Vish Ishaya, that solved my question.