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Disk shelves dont have the same amount of drives - 8400
https://3parug.com/viewtopic.php?f=18&t=2829		 Page 1 of 1
Author:  Koobster [ Tue Mar 20, 2018 7:12 pm ]
Post subject:  Disk shelves dont have the same amount of drives - 8400
I am taking over a 3PAR 8400 4node from a department that is no longer with us. It was initally installed but wasnt used and just sat in the datacenter. It has a weird layout as it has 40 10k drive and a total of 8 disk enclosures (2 shelves from the 4 node controller + 6 additional shelves). So half of the disk enclosures have 4 drives and the other half has 6 drives. I think they were going to only run raid 1 cpgs.

Anyways what are some issues that i can expect with this system not having the same amount of even drives on each enclosure? Obviously i can see this effecting the CPG configuration and HA choices as well as maybe unbalanced load for the node pairs.... but what else?
Author:  MammaGutt [ Wed Mar 21, 2018 2:22 am ]
Post subject:  Re: Disk shelves dont have the same amount of drives - 8400
With large set size and ha cage you could end up with capacity not being able to achieve ha cage. If is split so one node pair has 6 disks in the enclosures and the other has 4 you will see more data stored per drive on the nodes with 4-disk cages.

I'm guessing someone was thinking 40 is dividable by 8 and forgot that drives need to be installed in pair per cage.
Author:  Koobster [ Wed Mar 21, 2018 1:23 pm ]
Post subject:  Re: Disk shelves dont have the same amount of drives - 8400
MammaGutt wrote:
With large set size and ha cage you could end up with capacity not being able to achieve ha cage. If is split so one node pair has 6 disks in the enclosures and the other has 4 you will see more data stored per drive on the nodes with 4-disk cages.

I'm guessing someone was thinking 40 is dividable by 8 and forgot that drives need to be installed in pair per cage.


I checked PD/cage ownership and each node pair owns the same amount. 2 drive cages w/ 4 drives, and 2 drive cages w/ 6 drives.
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