Increasing harddrive size

[Theaterman72]

I'm in the process of building a new FreeNAS server and want to know if the following will work and if it's difficult to do.

I have a great deal on 2 X 2TB drives. I'm going to be building a RaidZ2 with 6 drives

2X2TB and 4X1TB

If I understand correctly max storage will be 4TB.

In the future, I'd like to upgrade the 4X1TB to 2 TB for a total storage of 8TB (Give or take for the over head I know it's not exactly 8TB)

If I understand correctly the storage space will only increase after I've upgraded all of the drive, is that correct?

Will the change be auto matic or do I need to do something for it to take effect?
Do I need to back up my data? Or do I just replace one drive at a time and there is no need to backup?

I know this is a lot of questions, but I'm sure someone out there can point me in the right direction. Thanks

 

[fracai]

I did exactly this when I started my system. Replacing each drive will take a while, but when you finish replacing the final drive you should have the increased space. Just make sure that your pool has the "autoexpand" property set and it'll be fine.

Generally, you should run a scrub, perform the drive swap, replace the drive in ZFS, wait for the resilver, remove the old drive from ZFS, perform the next swap. A resilver is basically a scrub so there's no need to scrub after each.

Oh, and do you "need to back up your data"? It should already be backed up. Resilver is hard on drives so it's good that you're planning on Z2, but "RAID is not a backup"(TM). If everything goes fine you shouldn't need restore any data, but if you have two failures during the resilver you will still lose data.