topic Re: Aggregate and RAID Group Sizing in ONTAP Discussions

Aggregate and RAID Group Sizing

QHALO1313 — Thu, 05 Jun 2025 06:22:03 GMT

Hello,

We
recently purchased 2 2240-2's with the following configuration of disk shelves, one complete setup for each site. I'm having some questions
regarding configuration of the RAID groups and how best to present the storage.

4xDS2246 600GB SAS 10k - 24 drives each

1xDS4243 3TB SATA - 12 drives

600GB SAS ~ 558.91GB actual

3TB SATA ~ 2.72TB actual

My consideration was for the following configuration for one of the two sites(both sites will be the same configuration):

Controller 1 -

RAID-DP

1 aggregate - 64bit

5 raid groups of 18 drives = 2 parity + 16 data drives

96
total drives = 3 ONTap drives for HA Pair + 10 parity for all RGs + 3 hot spare for the aggregate + 80 data drives usable capacity

80 data drives = 44.7TB * (1- ( .10 WAFL overhead + .20 Snapshot reserve)) = 43.5TB * .7 = 31.298TB actual space

Controller 2 -

RAID-DP

1 aggregate - 64bit

1 raid group of 12 drives = 2 parity + 10 data drives

12 = 9 data drives + 2 parity + 1 hotspare

9 data drives = 24.48TB * (1- (.10 WAFL overhead + .20 Snapshot reserve)) = 24.48 * .7 = 17.136TB actual

Am
I thinking about this correctly? This looks to be the best configuration that I can come up with that both maximizes my capacity and gives me the protection I need. Please critique.

Re: Aggregate and RAID Group Sizing

RodrigoNascimento — Fri, 27 Jul 2012 19:10:26 GMT

It looks fine!

Usually and when possible I prefer to put SATA drives for one controller and SAS drives to the other like you did.

After put your environment information at "Storage Design Studio" I have this for you:

Controller1:

Assign 96 SAS disks;

Leave 2 for hot-spare;

Create an RAID-DP aggregate with 94 SAS disks with RAID Group Size of 19;

At the end you will have 40.3 TiB Aggregate;

Controller2:

Assign 12 SATA disks;

Leave 1 for hot-spare;

Create an RAID-DP aggregate with 11 SATA disks;

At the end you will have 19.6 TiB Aggregate;

In this way, your total capacity for this system will be 59.9 TiB.

I hope it help !

Rodrigo

NetApp - Enjoy it!

Re: Aggregate and RAID Group Sizing

QHALO1313 — Fri, 27 Jul 2012 19:15:09 GMT

Rodrigo,

You are the man. Thanks a ton!

Am I correct in my assumptions about WAFL and SnapShot Reserver overhead? From what I read, it looks like 70% of usable space is a safe estimate taking all things into consideration.

Re: Aggregate and RAID Group Sizing

RodrigoNascimento — Fri, 27 Jul 2012 19:22:03 GMT

WAFL is 10%

About Snapshot Reserve, 5% is the default value for Aggregate Snapshots and 20% is the default value for volume snapshots.

Don't forget to rate the answer as "Correct Answer" or "Helpful Answer".

Rodrigo

NetApp - Enjoy it!

Re: Aggregate and RAID Group Sizing

QHALO1313 — Fri, 27 Jul 2012 19:45:08 GMT

I wish I knew how I could change the question to Answered.

Re: Aggregate and RAID Group Sizing

RodrigoNascimento — Fri, 27 Jul 2012 19:48:50 GMT

I don't know how to do this .... jajajajaja

Man, don't worry about it, the important is help each other.

All the best,

Rodrigo

NetApp - Enjoy it!