IOPS, latency, throughput calculation (in case msa 2052)

[borokabokor]

Dear All,

I read a lot of docs on web in the topic, however the more I read the more question I have. Beyond the main iops calculation for the raid arrays (which includes the write penalties), I'm a bit lost how to calculate total iops (and latecy, throughput) for a hybrid pool in theoretically. (I'm thinking in msa 2052). 

1)In a raid5 or raid6 using more disk than the minimum, the total iops calculated with the total disk number with the parity disk(s) or without those?   

2)In a capacity tier pool includes  raid1 2xSSD with oips X and raid5  6x10k sas with iops Y. Is the calculated total will be its sum (X+Y)?

3)In case of using read cache (for example 2x800Gb ssd in raid1) what is the general method to guess the read cache usage (%) and how can it summarize with the underlying pool iops capability to get a roughly total? 

Thank you very much

[AnilThakurHPE]

Hi ,

All you answers related to performance is mentioned in the below link , which is a quickspec guide for MSA2052.

Kindly refer page number 9 and 10 thoroughly .

Once you have the setup ready , as per the benchmark defined in the doc, you can measure performance matrix directly from web or cli console of MSA 2052.

Refer the below link-

https://h20195.www2.hpe.com/v2/getdocument.aspx?docname=a00008277enw

Thanks,

Anil@HPE

[borokabokor]

Thank you for your answer. However I still don't understand how to calculate mixed config, because those tests are made with only ssd or only hdd. So If I would like to set up a system which capable of random rw 20.000 IOPS in a Raid5 config, I could buy 180 15K HDD (from the table number 6 Raid5 HDD 29,100 IOPS; 16GB FC). But I don't want to buy so much hdd so

I could buy only 18 (2x9 for poolA and poolB), which will be 2910 IOPS. (I think i'm right if I simple divide the above). Then I said it is far from the desired so I would speed up this with some ssd. But how?

A) Using performance tier:  If I buy 6 ssd (from table  number 12) which 80000 IOPS the result will be the sum of the two disk group? 80000+2910 =82910 IOPS? In every circumstances ? Becuase if somehow it falls back to the hdds iops it is far form the required 20000 IOPS... So it is not so clear for me.

B) Adding caching tier : it is completely a dark patch for me, how the read cache is alter the underlying hdd performance / iops. Because it is a read cache I suppose it is only meaningful in case of read operations. But how can I roughly calculate with this options? In addition if I right I can not use both the performance tier and read cache for the same pool.

So could somebody help me how people planing capacity and speed? (maybe there is a general procedure , which is not only applicable for hpe)

You wrote: "Once you have the setup ready , as per the benchmark defined in the doc, you can measure performance matrix directly from web or cli console of MSA 2052."

You mean there is a web page where I can add configuration and that shows me an approximately calculation? I would like to "measure" before I buy

thank you very much