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

[sourcecorp_lee]

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

[scottgelb]

Yes. Write sizing. Block checksum and wafl

[ashleycook]

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

[sourcecorp_lee]

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

[scottgelb]

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

4

Disks

96

Data Disks

80

TB Usable no snaps

110.0447

Spare

Data

Parity

spare

6

rg0

16

2

rg1

16

2

rg2

16

2

rg3

16

2

rg4

16

2

[sourcecorp_lee]

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.