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On 8/18/2018 10:20 PM, Matt Riedemann wrote:
> On 8/13/2018 9:30 PM, Rambo wrote:
>>         1.Only in one region situation,what will happen in the cloud 
>> as expansion of cluster size?Then how solve it?If have the limit 
>> physical node number under the one region situation?How many nodes 
>> would be the best in one regione?
> 
> This question seems a bit too open-ended and completely subjective.
> 
>>         2.When to use cellV2 is most suitable in cloud?
> 
> When this has been asked in the past, the best answer I've heard is, 
> "whatever your current DB and MQ limits are for nova". So if that's 
> about 200 hosts before the DB/MQ are struggling, then that could a cell. 
> For reference, CERN has 70 cells with ~200 hosts per cell. However, at 
> least one public cloud is approaching cells with fewer cells and 
> thousands of hosts per cell. So it varies based on where your 
> limitations lie. Also note that cells do not have to be defined by DB/MQ 
> limits, they can also be used as a way to shard hardware and instance 
> (flavor) types. For example, generation 1 hardware in cell1, gen2 
> hardware in cell2, etc.
> 
>>         3.How to shorten the time of batch creation of instance?
> 
> This again is completely subjective. It would depend on the 
> configuration, size of nova deployment, size of hardware, available 
> capacity, etc. Have you done profiling to point out *specific* problem 
> areas during multi-create, for example, are you packing VMs onto as few 
> hosts as possible to reduce costs? And if so, are you hitting problems 
> with that due to rescheduling the server build because you have multiple 
> scheduler workers picking the same host(s) for a subset of the VMs in 
> the request? Or are you hitting RPC timeouts during select_destinations? 
> If so, that might be related to the problem described in [1].
> 
> [1] https://review.openstack.org/#/c/510235/
> 


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Thanks,

Matt