120TB FreeNAS Build Questions

[swamiforlife]

Hey All,
I am planning on building a FreeNAS Server for a local non profit organization.
We have a 12bay supermicro server and 12 10TB HGST NAS drives and it has 96gb of RAM.
The problem is we wanted to use raidz2 for this setup.
What is the best way to configure the storage in FreeNAS that provides redundancy and good read and write performance.
Since I'm new to FreeNAS, how many disks should be in vdev?
How many vdevs should i setup and how many zpools, etc?

The server will be used for Windows shares. So is a write caching SSD necessary? If so how big should it be?
In our environment the server will have both reading and writing will be going on.

We need to have around 80TB-100TB usable space after the setup is completed.

 

[m0nkey_]

Since I'm new to FreeNAS, how many disks should be in vdev?

I would create two 6 drive RAIDZ2 vdevs and put them in the same pool. This should give you reasonable speeds as well as decent redundancy.

is a write caching ssd necessary?

Not in your use case. A SLOG or L2ARC devices is not required.

 

[diedrichg]

((6 @ 10TB) x 2) RAIDZ2 ~= 57.28TiB usable

 

[swamiforlife]

((6 @ 10TB) x 2) RAIDZ2 ~= 57.28TiB usable

Wait that that final usable doesnt make sense to me. (6 x 10TB) RaidZ2 = 36.37Tib Usable.
Since there will be 2 Raidz2 vdevs * 36.37 ~= 72Tib
So am i making a mistake with my calculation.

 

[diedrichg]

Hmm. You are correct. I need to check my spreadsheet for accuracy. Here is a calculator one of our members created:

https://jsfiddle.net/Biduleohm/hfqdpbLm/10/embedded/result/

Edit: ah, I see the issue. If you have 6 drives, 2 are for parity. Two sets of those = 4 parity drives. 12 drives with 2 parity would certainly get 72TiB.