How to add disks to a Volume?

[tmacka88]

Hey I thought that you could add disk to a RAID-Z setup by selecting disk and naming it the same as the volume you would like to add it to but, I read in the freenas FAQ's differently.

This is what it said....

"Can a RAID-Z array be expanded? For example, if I start off with a 8x2TB RAID-Z2 array can I add more drives to it in the future?
A. You can add drives to a volume, but not to a RAIDZ group. For example, if your volume is a 3 drive RAIDZ, you can add another 3 drive RAIDZ in the future, giving you a RAIDZ+0. But you can't change it to a 4 drive RAIDZ. This a limitation/feature of ZFS."

Now i want a RAID 5 or RAID-Z array but able to expand my HDD storage by adding more HDDS in the future and only having 1 sharing volume and 1 volume where you can add 1 disk at a time to it e.g start with 3x2tb like i have now but in the future add anotherr 2tb and some on.

can this be done?

 

[Durkatlon]

Well, yes, you can do this in ZFS, but the new disk will form a stripe together with the old RAIDZ. So as you add more disks you will add more and more virtual devices that form a stripe with the originally redundant device (the RAIDZ) but overall the volume is no longer protected against disk failure (unless you get lucky and one of the disks in the original RAIDZ fails).

What you normally want to do is add multiple disks at a time. So if you had a 3 drive RAIDZ, you should expand by adding another 3 drive RAIDZ to the same volume. The two RAIDZs will form a stripe which together constitutes the entire volume..

You don't have to add 3 drives at once, you could add 2 (as a mirror) or 4 (as a RAIDZ or RAIDZ2), or even more. The point is that you want to add multiple drives so the newly added drives form a device that has redundancy.
The main point is that you will be adding new virtual devices (VDEVs) this way, not add disks to the existing VDEV.

I hope this makes sense.

T

 

[matthewowen01]

you have several options to grow storage:

you can replace every disk, one by one in a vdev with larger disks to grow.

you can add a new vdev to an existing pool, this vdev should be of the same type as the existing vdevs. so if you have a pool with a raidz vdev, you can add a new vdev that is a raidz.

you can add one disk at a time but you will not have any redundancy. start with a single disk, then add them one by one. however no redundancy should cause you to not choose this option. you could do something similar with mirrors though. start with a mirror then add sets of mirrors.


i personally avoid raidz and single mirrors as they only have a single of redundancy and if you have a disk failure, you have no redundancy until you get your replacement which can be several days. i would go with a raidz2 of as many disks as you can afford.