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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Jan 28, 2019 6:45 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
https://h20195.www2.hpe.com/v2/getdocum ... 0000244enw

URE

Biggest reason ever to run RAID6. Full 4TB SSDs, R5 7+1. Disk failure (ignoring spare and that stuff) will need to read n* disk size (where n is the R5 n+1). So that will read 7*4TB = 28TB of data. With one URE every ~1 PB of data you have a ~2.8% of URE (or about 1 in every 40).

This is generic for the entire storage industry and the reason why (as far as I know) no storage vendors recommend single-parity RAID on any enterprise storage systems anymore.

If you chose performance (yes R6 will have ~65% more backend IO for write compared to R5, read is still just a single IO for both) over data security, then I hope you've cleared that with the guys in the suits and with the higher pay grade. Because they will not be happy the day you hit that URE with RAID5, and it is only a matter of time.

If capacity is important, R6 14+2 is an option.


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 Post subject: Re: Adaptive Optimization
PostPosted: Thu Jan 31, 2019 3:19 am 

Joined: Thu Mar 01, 2018 3:04 am
Posts: 15
Hi,

I have applied this actions:
- Remove unused VV on CPG_FC_R6_8D2P
- launched compactcpg to retrieve space
- Storage Vmotion the 2 only VM that on CPG_SSD_R5_7D1P
- Remove the 2 VV that on CPG_SSD_R5_7D1P
- compactcpg
- configure AO to Tier0 on new CPG_AO_SSD_R5_7D1P and Tier1 on CPG_FC_R6_8D2P
- Disable FlashCache

AO has moved block to SSD and used 999GB.
IOPS have lower on FC disks (cf attachment statpd -d 10 -p -devtype FC)

But my SSD space is full:
SSD
Total 2 968 GiB
Allocated2 646
Free 322

I f i refer to ninja star, with 8 x 400GB, with R5_7D1P, i must have :
RAW 2.9
Usuable 1.9

but I used 999GB for AO, and not another space are allocated to SSD
I have run compactcpg after remove VV but the array still that is already compacted.

so my question, where is the another space or it's normal ?


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 Post subject: Re: Adaptive Optimization
PostPosted: Thu Jan 31, 2019 6:13 am 

Joined: Thu Mar 01, 2018 3:04 am
Posts: 15
Error, i have just disable the flash cache but it still configured.
after de-configured it, i have retrieved space (now 869GB free)


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 Post subject: Re: Adaptive Optimization
PostPosted: Thu Jan 31, 2019 8:41 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
Well, that's magic... I mean AO :)

As long as all volumes has FC CPG has "User CPG" you can allow SSD tier to go completely full, so based on your numbers AO can still move 2x the amount of data up to SSD tier. Give it a few more days and it probably will.

If you want to look at how much of you "hot data" is staying in the same place, you can check with srrgiodensity commands and you've mastered statvv (as you've filtered on FC drives) to check how your SSDs and FC drives are doing.


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 7:46 am 

Joined: Thu Mar 01, 2018 3:04 am
Posts: 15
Hi,

AO was working fine :
- i have launch AO wednesday
- the next saturday, AO has filled SSD Space (hight alert on 3par !)
- but the tomorrow (sunday), AO has empty 800GB of data on SSD Space

So I have this questions:
- is it possible to disable the healthy alert about SSD Space is full ?
- why AO has empty some data ?
- do I need to wait one week and let AO to analyse the activity ?

Thanks,


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 8:39 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
abelliot wrote:
So I have this questions:
- is it possible to disable the healthy alert about SSD Space is full ?
- why AO has empty some data ?
- do I need to wait one week and let AO to analyse the activity ?

Thanks,


1. Run this command in CLI: setsys RawSpaceAlertSSD 10
2. AO will move "hot blocks" to higher tiers and "cold blocks" to lower tier. Sounds like your shop might be a Mon-Fri 9-5 shop and in those cases it might be best to only run AO 5 times per week.
3. AO will move blocks based on analysis of the time slot you specify in the task. So if you specify 7AM to 6PM and run the task at 9PM it will only look at data for that day between 7AM and 6PM.


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 8:45 am 

Joined: Thu Mar 01, 2018 3:04 am
Posts: 15
Thanks,

I have also found the parameter for SSD

I have schedule this:
from tuesday to saturday
start time: 01am
runtime: 06h
start analysis: 18h prior
duration: 12h
so i analyse from 7am to 7pm

am i right ?


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 9:12 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
abelliot wrote:
Thanks,

I have also found the parameter for SSD

I have schedule this:
from tuesday to saturday
start time: 01am
runtime: 06h
start analysis: 18h prior
duration: 12h
so i analyse from 7am to 7pm

am i right ?


Just be advised that (unless something has happened) setsys RawSpaceAlertSSD 0 will set the alerts to default (50/75/85/95% or something) while setsys RawSpaceAlertSSD 10 will set it so low that it should never trigger.

And yes. Your analysis period will be Mon-Fri 7AM-7PM with execution 1AM the following night with that configuration. So you will not run AO on Sunday morning and Monday morning.


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 9:24 am 

Joined: Thu Mar 01, 2018 3:04 am
Posts: 15
ok, do you think i need to also schedule on monday morning.
when I see statpd , i still find that fc disks with low water mark


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 Post subject: Re: Adaptive Optimization
PostPosted: Mon Feb 04, 2019 11:10 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
Monday morning will be based in Sundays load. If you think the load is more equal to Sunday than Friday (Saturday morning AO run) then you should run on Monday, if not you should drop it in Monday.


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