ONTAP Discussions

How to get optimal usable capacity from new aggregate.

ARSEN3790
1,648 Views

Hello,

 

I have a FAS8020 and to which I added 2 DS4243 24x1TB disk shelves. I created the new aggregate with the following configurations:

 

45 Disks 2 spares

 

Raid-DP

 

Raid size 15

 

3 raid groups of 15 disks each

 

total space is 28.37 TB 

Available space is 28.37 TB 

 

I was hoping to see way more usable space but it seems that Ontap is taking 19 TB for its self which seems way to high.

 

Can someone please help me determine how I can get the most space out of the aggregate.

 

Thanks,

 

Arsen B.

 

1 REPLY 1

junwang
167 Views

Hi, ARSEN3790

Firstly, the system requires three disks, which reduces the total capacity by 3TB. Then, two spare disks reduce the total capacity by 2TB. Each raidgroup will have two verification disks that cannot be used as data disks. If you create three raidgroups, it means that there are six disks that are verification disks, which reduces the capacity by 6TB. Therefore, the 11TB capacity will be lost. The actual available capacity is 28.37TB by multiplying the number of available disks and the capacity by the available capacity factor. Of course, the space is not enough. The following two suggestions are given.
1. Leave 2 spare disks out of 45 hard drives, resulting in a total of 43 data disks. The FAS8020 device creates two raidgroups with maxraidsize 21 and maxraidsize 22 on a single controller, resulting in 19 and 20 data disks for each group. The total capacity of the data disks in these two groups is 31.2TB.
2. Use disk partitioning to partition the disk, which reduces disk wear and increases available capacity. Suggest using the automatic partitioning function.

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