Convert RAID 1 to RAID0+1 (4 drives)

Only a RAID 0 volume can be converted to RAID 1+0.

So yes, you need to back up, then create a new volume.

Alternatively you could split both mirrors, create a stripe volume, copy the data onto it, then convert the stripe to RAID 1+0.

Only a RAID 0 volume can be converted to RAID 1+0.

So yes, you need to back up, then create a new volume.

Alternatively you could split both mirrors, create a stripe volume, copy the data onto it, then convert the stripe to RAID 1+0.

So, do I create a stripe volume with drives of equal size (2 2TB or 2 3TB) or do I create a stripe volume with a 2TB and a 3TB (if that's possible)?

Create the stripe volume with the 2 3TB drives. Then when the data is copied over, when you insert the two new 3TB drives, you can convert the volume to RAID 1+0, with redundancy. Not too complicated.

Create the stripe volume with the 23TB drives. Then when the data is copied over, when you insert the two new 3TB drives, you can convert the volume to RAID 1+0, with redundancy. Not too complicated.

Please correct 23TB typo for clarification. No, not too complicate, but just want to be absolutely sure with mission critical data.

I noticed all your drives are 2TB,except one. So you need to create a 4TB drive stripe volume with a pair of 2TB drives. then you can convert that to a 4TB RAID 1+0. All partitions in a RAID volume are the same size. So there is no point to mixing drive sizes, you are limited by the smallest drive in your set of disks.

Actually I had two 3TB drives (I was still certifying the 2nd on another machine)

Here's what I ended up with, not exactly what I wanted, but another purchase of a pair of 3TB drives will fix that. The consolation prize is that SoftRAID can make a striped volume out of the unused space on the 3TB volumes.

Couldn't be easier, SoftRAID makes it a snap.

Excellent!

Okay, two hours away from a 3-day certify of a new pair of 3TB drives.

I will be replacing MacPro's Bay 2 & 4 2TB drives with brand new 3TB drives. I would like to know how to do this. Just replacing one volume at a time should just work for the RAID 0+1 volume. Both 2TB drives are secondary disks of different "mirror pairs". Can I replace both 2TB disks at once?

Is there anyway to add unused space to a RAID 0 (stripped) volume making it bigger without losing data?

We can only convert a stripe to a RAID 1+0

to keep both volumes, here is something. It will require copying data.
Take the new drives and create a stripe volume.
Copy all the data to it.
Then initialize the two older 3TB drives.
Convert to RAID 1+0.
That is probably simplest.

Will I have access to both volumes Judah & Tunes is I replace both 2TB drives in the RAID1+0 & Stripe format?

You could replace disks in a Mirror from 2TB to 3TB, and after that is done, expand the volume.

If you have both a stripe and RAID 1+0 on the same set of disks, the stripe data would be lost if you try to replace a disk.