planning disk count expansion for the next few years

[cyris212]

I'm planning to build myself a FreeNAS box, that can handle up to 12 4TB drives. I'm going to store a couple of different things onto it:

- Calendar, Contacts and Files (ownCloud)
- Logs and Configurations from other network devices using rsync
- Movies and TV Shows (pyLoad)

I want to start with a 4 drive RAID10 and add drives in the next couple of years up to 12 4TB Drives. What would be the best way to add the drives later on?

Do I need to create for each 4 disks another RAID10/zpool? Or is there a way to add a zpool to a zpool ?

 

[danb35]

Each mirrored pair of disks will be one vdev. Your initial configuration, as you describe it, will be two such vdevs striped together in a single pool. When you add pairs of disks in the future, each pair will be a new vdev, which will be added to your existing pool (you can create a new pool if you choose, but you don't need to).

 

[pschatz100]

How do you plan to add drives in the future and what is your capacity target?

For instance, an alternative to two striped mirrors would be starting with a 4 disk RaidZ2. Same capacity, a bit better redundancy in that any two drives could fail without losing the pool. If you plan to add new drives 4 at a time, you could add a second 4 disk Raidz2 and then later a third 4 disk Raidz2. At the end of the day, your total capacity would be equal to 6 formatted disks.

Just for the purpose of discussion, if you were to start with a six disk raidZ2, then add six disks later as another six disk raidZ2, you would have a bit less redundancy than above, but your total capacity would be equal to eight formatted drives.

Cyberjock has a nice presentation that provides an introduction to ZFS. You can get an overview of ZFS and a discussion of capacity versus redundancy. Look for it in the stickies.