Hey guys,
I am fairly noobish regarding zfs and have so far only set up a Freenas server with two striped disks. I just bought two 6TB disks and have another one in use. My end goal is to have a 2+1 raidz on either Freenas or Unraid.
Now to the question: Is it possible to stripe two hdds together and add another one later for redundancy?
When you build a zpool, you expand it in increments that you initially set it up with, so if you start with two disks in a mirror, you can stripe in another two disks in a mirror, effectively raid 10. To expand more, add another two disks, etc. With ZFS you must plan your expansion ahead of time. If you want an effective raid 5, you should really nuke the pool and build again. If you want to mirror your stripe, I think you can, but really striping mirrors is better practice.
Ok, thanks for the reply. I was playing around with .img-Files for testing but couldn’t get working. In the end I settled for buying a third 6TB drive and just reselling that again once I build the raid, transfered all my data and of course shred all the data from temporary drive.
I highly recommend against running a zpool in degraded mode for a long period of time. I highly recommend keeping that additional disk.
Mirrored stripes provide the absolute best performance, while still maintaining failure tolerance.
I think you misunderstood. My plan is as follows:
I got one hdd with data already on it. Let it be A.
I bought 3 hdds. Let them be B, C, D
A, B, C, D are all the same model.
Copy A -> D.
Build raidz (2+1) / raid 5 from A, B, C. Let it be X.
Copy D -> X.
Overwrite D at least twice with /dev/urandom.
Sell D as “used once”.
As I see it, the pool will never be degraded in that process, or am I missing something?
Ah, I did misunderstand. This is a sound strategy.
No, you will have to create a new pool with the correct layout. You can’t fix striped vdevs at the top level.