Replacing drives

[piotr.g]

Hello all!

I currently have a ZFS Virtual Device consisting of 4 x 500GB disk set up as RaidZ1. I then created a Pool of this Virtual Device.

I am receiving 4 x 3TB disks next week and I was hoping someone could tell me what would be the best way to migrate the data from the 500's to the 3TB's.

I have a bunch of services setup up such as bittorrent and owncloud and would prefer to keep the configuration without having to recreate it on the new drives.

Thanks in advance!

[ku-gew]

You take one disk out, you replace it, you wait for rebuild.
Repeat for each disk.

Each rebuild will take a while...

[piotr.g]

Oh great! I was hoping it would be something simple like this! Thank you ku-gew.

On a different matter, if in the future I got another 3TB disk, would I be able to "grow" this pool by adding it?

[Onichan]

You can't grow by just adding disks. Only by either replacing the drives like you are now or by adding more vdevs to a pool. Pools do NOT provide data redundancy, it is the vdevs that do that. So if you want to add another vdev to your pool to grow it then you would need to ensure that vdev has redundancy. So in your case it would be recommended to add 4 more drives in RAIDZ1 into its own vdev and add that to the pool. Though you technically could just add either two in a mirror or three in RAIDZ1 and it would still work.
Though personally with you now going to 3TB drives I would say you should look into upgrading to RAIDZ2 as your vdev datasize is getting large and you can run into this problem http://www.zdnet.com/blog/storage/why-r ... n-2009/162

[ku-gew]

I calculated 51% probability to experience unrecoverable errors during rebuild with a 3+1 RAID5 using consumer 3TB disks.
I don't know if this means losing everything or only some sectors of the disk, but the probability to have to face it is 51%.
Use RAIDZ2 if you want to reduce this risk significantly.

And of course when I wrote "take one disk out" I meant "look for the correct way to do that, don't just disconnect the disk"!

[piotr.g]

Thank you all for the replies.

Let me see if I understand this correctly. Currently with a 4 disk setup I can't do RAIDZ2, so I would need to purchase another 3TB drive for RAIDZ2. I suppose I can't create a RAIDZ1 setup now and then once the next 3TB disk arrives, upgrade everything to RAIDZ2? Would I need to then recreate the whole raid setup from new as RAIDZ2?

[raulfg3]

I suppose I can't create a RAIDZ1 setup now and then once the next 3TB disk arrives, upgrade everything to RAIDZ2?

wrong suppose.

please read this article to understand how ZFS work: http://forums.freenas.org/showthread.ph ... light=.ppt

[fsbruva]

If you are eventually planning on upgrading to a 5 drive RAIDZ2 vedev, it would seem to be better to wait and build it all at once, rather than risk the 51% chance that you lose everything.

How much data are we talking about? How many hard drive connections do you have available? (probably not 9, but I am just guessing). How many computers do you have, also?