topic What is the effective size of a 2TB Netapp disk ? in ONTAP Discussions

What is the effective size of a 2TB Netapp disk ?

sourcecorp_lee — Thu, 05 Jun 2025 06:28:02 GMT

We just added 2TB disks to our FAS6280 filers and they show up as 1.62TB. Is that right ?

Re: What is the effective size of a 2TB Netapp disk ?

scottgelb — Fri, 04 May 2012 14:57:15 GMT

Yes. Write sizing. Block checksum and wafl

Re: What is the effective size of a 2TB Netapp disk ?

ashleycook — Fri, 04 May 2012 15:08:29 GMT

As Scott has mentioned, yes that is correct.

For reference there is a handy table within the Storage Management Guide:

https://library.netapp.com/ecmdocs/ECMP1114070/html/GUID-5D3F3F2D-A153-49D3-9858-04C30B3C7E74.html

This gives a 2TB disk as:

Disk size as described by manufacturer	Physical capacity (approximate)	Usable capacity
2 TB SATA	1,695,702 MiB	1,695,466 MiB

For the full how and why, KB 3011274 covers it:

https://kb.netapp.com/support/index?page=content&id=3011274

Re: What is the effective size of a 2TB Netapp disk ?

sourcecorp_lee — Fri, 04 May 2012 15:17:31 GMT

Ok. Just wanted to make sure this was correct before I started using them. That would explain why they sent us 96 drives to satisfy a 100TB usable order.

Thanks

Re: What is the effective size of a 2TB Netapp disk ?

scottgelb — Fri, 04 May 2012 15:27:30 GMT

You should get about 110TB usable without snapshots… an example layout with 18 drive raid groups (leaving 6 spares..more than you need but not enough for another complete raid group) assuming all on the same controller but you could split between controllers.

DS4243 Shelves

Disks

Data Disks

TB Usable no snaps

110.0447

Spare

Data

Parity

spare

rg0

rg1

rg2

rg3

rg4

Re: What is the effective size of a 2TB Netapp disk ?

sourcecorp_lee — Fri, 04 May 2012 15:47:14 GMT

Thanks for the info. We split them between 2 controllers in an active/active cluster, so there were 48 disks per controller. Some were used to expand an existing aggr and the rest were grouped into a new aggr.