Open Stack

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/

-- 

Thanks,

Matt