topic Re: Largest optimal SATA 500 GB aggreggate under 7.3.1 in ONTAP Discussions

Largest optimal SATA 500 GB aggreggate under 7.3.1

evilensky — Thu, 05 Jun 2025 07:29:55 GMT

Would the largest aggregate to be constructed under 7.3.1 is would be of RG 12+2, 12+2, and 10+2? The 34 data disks would be 465.66 GB each, adding up to 15,832.44 GB of storage? ( aka < 16 TB without parity)

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

amiller_1 — Wed, 18 Mar 2009 00:27:49 GMT

A couple thoughts here....

First, under 7.2.2 I was able to make a 39 disk aggregate using 500 GB SATA disks - (3) RAID groups of 13 disks each. Yes, that's beyond the 16 TB space limit but it did work....go figure.

Second, under 7.3 the rules have changed in that the parity disks aren't counted -- you can now have 39 500 GB data disks in an aggregate. Given (3) RAID groups of 13 data disks each (with 2 parity disks each), the largest aggregate you could make with 500 GB SATA disks would actually be 45 disks total.

http://now.netapp.com/NOW/knowledge/docs/ontap/rel731_vs/html/ontap/rnote/rel_notes/reference/r_oc_rn_feat73_aggr-size-max-drives.html

This link actually confirms the setup I mentioned under 7.2.2 (although I couldn't find any reason why it worked at the time).

If you're looking at 3 shelves though, I'd probably do (2) 13 disk RAID groups and one 14 disk RAID group -- 40 disks total and keep 2 spares. If 6 shelves, you could do (2) 41 disk aggregates -- would mean each aggregate would have (1) 13 disk RAID group, (2) 14 disk RAID groups, and would leave 2 hot spares overall. If doing 6 shelves via MPHA, 4 GB FC backend bandwidth would be sufficient I think.

Side-note: doing big SATA aggregates does help alleviate the IOP limitations.

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

pascalduk — Wed, 18 Mar 2009 09:09:55 GMT

amiller@dnscoinc.com wrote:

First, under 7.2.2 I was able to make a 39 disk aggregate using 500 GB SATA disks - (3) RAID groups of 13 disks each. Yes, that's beyond the 16 TB space limit but it did work....go figure.-

The physical size of a 500 GB SATA drive is not 500 GB but 423 GB. With 423 GB you will right on the 16 TB limit in your calculation.

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

amiller_1 — Wed, 18 Mar 2009 11:09:30 GMT

Yes, that was my guess.....the part that never made sense to me was...

423 GB * 39 disks = 16,497 GB / 1024 = 16.11 TB (definitely over the 16 TB raw limit)

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

evilensky — Wed, 18 Mar 2009 14:09:48 GMT

Where does 423 GB number come from? Useable space after WAFL formatting? 500,000,000,000 bytes = 465.66 gigabytes

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

evilensky — Wed, 18 Mar 2009 14:17:34 GMT

Hmm the filer reports 413 GB used for each 500 GB SATA disk in an aggr, so is this the number to use when attempting to max out an aggr? Is there an Aggregate Sizing TR that we can refer to?

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

evilensky — Wed, 18 Mar 2009 14:19:17 GMT

Thank you for the rel notes link. It answers mostly my questions and I should have referenced it first.

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

pascalduk — Wed, 18 Mar 2009 15:37:41 GMT

Yes, 423889 MB physical and not 423 GB as mentioned before

Re: Largest optimal SATA 500 GB aggreggate under 7.3.1

amiller_1 — Fri, 20 Mar 2009 22:42:57 GMT

Ah....you're right. I thought I remembered it as 423 GB in FilerView but it is indeed 413 GB.

In that case, 413 GB * 39 = 16,107 GB / 1024 = 15.73 TB.