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 Post subject: Multipe AO groups on the same disks
PostPosted: Mon Feb 05, 2018 5:43 am 

Joined: Fri Jul 17, 2015 6:08 am
Posts: 25
We have added some more disk space to our systems and are going to re-create our AO CPGs so we can modify the step size to reflect the number of disks and set size in each tier.

Should we stop our current AO tasks/schedules or can we have both AO tasks running at the same time? If we have 2 AO tasks trying to run concurrently, will they conflict?


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 Post subject: Re: Multipe AO groups on the same disks
PostPosted: Mon Feb 05, 2018 2:44 pm 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 590
You could be "lazy" and simply edit your existing CPG and run tunesys. That way you don't need to tune all your volumes to a new CPG and wait for AO to push data up and down again.

You should stop AO while running that type of tunesys because there is a good chance they may conflict on some blocks leaving some LDs with the old set size.


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 Post subject: Re: Multipe AO groups on the same disks
PostPosted: Fri Feb 09, 2018 6:10 am 

Joined: Fri Jul 17, 2015 6:08 am
Posts: 25
We're not changing the set size. We want to change the Growth increment so that when the CPG increases in size, it always increases by (number of disks/(set size*(set size-1))) for our RAID 5 CPGs and (number of disks/(set size*(set size-2))) for our RAID 6 CPGs. This should mean each time a CPG grows, 1 chunklet from each disk available to the CPG is allocated to the CPG.

eg. RAID5, set size 7 (7 shelves), 42 disks. This should result in a growth increment of 36GB. If we don't tune our volumes between CPGs, we run the risk that the chunklets in use for a single volume might not be evenly balanced across all disks.


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 Post subject: Re: Multipe AO groups on the same disks
PostPosted: Fri Feb 09, 2018 9:38 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 590
Same should apply. Change your CPG and tune. Tunesys should tune everything that is in the CPG but not according to the rules.


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 Post subject: Re: Multipe AO groups on the same disks
PostPosted: Fri Feb 09, 2018 10:58 am 

Joined: Thu Apr 28, 2016 1:29 pm
Posts: 10
Last tunesys I did took 2.5 months :shock: :shock: :shock:


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 Post subject: Re: Multipe AO groups on the same disks
PostPosted: Fri Feb 09, 2018 12:26 pm 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 590
If you have a lot of NL capacity or a lot of big 10k drives I believe you. I usually put max threads and try to avoid NL... Those drives are slow and huge. Having to rewrite everything there takes weeks.


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