Noob ZFS questions

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Dec 16, 2011
Need some help planning an array
This Array will be used for home based NAS.. pictures, media, video storage. It need to support real-time recording from my SageTV server .. Typically 2 streams at 2GB/hour
Mostly a write once and read many situation.
Main goal in using ZFS is to prevent a single disk fault from taking it all down. The real critical data is backed up elsewhere.

The server is a Gigabyte P35 MB with 8 Gig Ram and runs ESXi 5.0. Freenas is a guest.

I have a mixed bag of disk... All Segates SATA II

Empty Drives
2x 750G (enterprise class drives ..from a caching appliance )
1x 1000G
1x 2000G

Drives with Data that needs to be kept
1x 1500G
1x 300 (old .. will go to another machine )

What I'd like to do is create an array that has the maximum 'protected' space out of the 1st 4 drives.
- Then migrate the data from the 1500 to the array.
- Then add the 1500 to the array

What is the best way to setup this array in FreeNas


Behold the Wumpus
May 28, 2011
Hi zoltran,

Assuming you want to run ZFS, there isn't really a way to add another (single) drive to an existing array.

Now that's not exactly true, but since FreeNAS does such a good job of masking the "virtual device" part of ZFS it's not obvious why so let me explain. When you make a volume you actually make a "virtual device" (a vdev) out of your disks and the filesystem goes on top that. You can expand a ZFS filesystem by adding additional vdevs to it all day long, and you can add a single drive (it's still a vdev) but when you do you will lose any redundancy the volume has.

This is where ZFS enterprise roots came from an environment where there could be dozens of drives and new storage was added by the bay (or rack) so creating new redundant vdevs was easy.



Dec 16, 2011
Thanks Will
I've created the server with the 5 disks. Total space 6Gig (2x 750, 1000G, 1500G and 2000G)
Can you point me to doc on best practices re allocating pools?
I want to use the NAS as follows
CIFS File Server
- Protected datastorage for videos, photos music.. personal/family files
- Backups (incremental .. lots of dupdata)
- Live Video
- Bit Torrent downloads

And as Iscsi target for a few VM's .

Any suggestions, pointers, links on how to allocate/define the disks / pools ?
Will ZFS be able to use 'all the space' on the larger drives, or will the 2x750's restrict the partition size on the larger disks.?
Would I be better of making two pools .. 1 on the 2x750's and the other on the 3 larger drives (1T, 1.5T, 2TB) ?
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