[pve-devel] adding a vm workload scheduler feature

[Thomas Lamprecht]

Il 17 novembre 2015 08:40:19 CET, Dietmar Maurer <dietmar at proxmox.com> ha scritto:
>
>> What do you think about it ?
>
>interesting
> 
>> 
>> As we don't have master node, I don't known how to implement this:
>> 
>> 1) each node try to migrate his own vms to another node with less cpu
>usage.
>>    maybe with a global cluster lock to not have 2 nodes migrating in
>both way
>> at the same time ?
>
>I assume it is hard to get this stable (just a feeling). On the other
>side, this
>would be simple
>to implement. Each node is responsible to move its own VMs, so you do
>not even
>need a lock.

A lock maybe should be there to only let one rebalancing action happen at any time to avoid out of control feedback loops.

>> 2) have some kind of master service in the cluster (maybe with
>corosync
>> service ?),
>>    which read global stats of all nodes, and through an algorithm, do
>the
>> migrations.
>> 
>> Don't known which way is better ?
>
>My plan was to integrate this into the HA manager, but then you only
>have the
>feature
>for HA enabled VMs.

That could still be done, adding a new service which uses the HA Environment class. With a lock and a status/command file a master wouldn't be necessarly needed.

>
>But the CRM code shows how to use a cluster wide lock to implement a
>'master'
>role.
>
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