Trying to replace disk in RAID 1

Apparently, you never actually set up SoftRAID. It looks like you were running Apple RAID.

You need to boot from another Thumbdrive or external disk with an 10.11 OS installation.

Run SoftRAID on it.

I would recommend this, which is more steps, but will work:
Create two volumes on your SoftRAID disk, one for the OS, the other for data.
Use Carbon Copy cloner to clone your data to the two volumes.
When it is done cloning, click on the boot volume in SoftRAID and "rebuild boot cache".
Then you can initialize the internal disk with SoftRAID.

Select the boot volume and "convert to Mirror". (Which will rebuild in a few minutes)
Select the data volume and "convert to Mirror".
You can restart now, from the SoftRAID volume. the data volume will rebuild in the background.

Hello SoftRAID Support,

Thanks for your helpful reply. I actually inherited responsibility for this server a couple of years ago, but I agree, that SoftRAID must have never been fully setup.

I'd like to re-iterate your instructions to make sure I understand what you're recommending.
You're suggesting that I boot the Mac mini from an external drive that has OS X El Capitan (aka OS X 10.11) on it.

Then I should install SoftRAID 5.5 on this external drive. I presume that I'll need to enter the registration code (or whatever it's called). Will this be a problem registering SoftRAID on this external drive since it's presumably already been registered once?

Next, I need to create two appropriately sized partitions on my external drive. Then I'll clone the Mac mini's two internal volumes onto these newly created partitions.

Next, I run SoftRAID's rebuild boot cache command.

Next, I initialize the Mac mini's internal boot drive. I would think this would erase the volumes but since you don't indicate that I need to clone anything back onto this internal drive, thus I assume that this initialize will NOT erase the hard drive.

After initializing the internal disk with SoftRAID then I convert it to a mirrored drive. During this process I'll be able to add the new hard drive. Will I be able to partition it during this process?

I'm also guessing that you're suggesting that I clone both volumes, just to be safe. If this is the case, I should mention that I already have a clone of the boot volume and Time Machine backups of the data volume. So, technically, I shouldn't need to invest the time to clone them again, right?

My last question, just to be clear, is when I start the rebuilds, while they can run in the background, do I _need_ to do this rebuild while still booted from my external drive or could I boot the mini off from its SoftRAID-initialized boot drive and then convert them to mirrors and do the rebuild? I ask this because I'd like to minimize downtown, if possible.

Thanks. --Tim

You can enter the license on that volume also. SoftRAID is a "one computer at a time" license. Or you can just use it in 30 day trial mode, which is fully functional.

You do not initialize the mini hard drive! yes,that will delete all data. The correct procedure is to use the "convert" capability of SoftRAID.

Initlialize the second disk. (the new one with no data on it.)
"Convert" your Mini hard disk to SoftRAID format. this will not delete any data on the disks.
"Convert to mirror" on the Mini boot volume. Let it rebuild
Convert to Mirror' on the other volume.
restart and it will rebuild in the background.

One more note:
SoftRAID may not be able to convert your existing setup, as you have degraded Apple mirror volumes. if that is the case, then you will need to backup, then create two volumes, and restore the data back to the newly created volumes. (and use the rebuild boot cache command at the end to enable your boot volume to be bootable.)

Thanks.
Now I'm clear on what needs to be done. Thanks for clarifying that you meant I should initialize the new hard drive. Then, I'll convert the mini's current healthy drive to a mirror and then let it rebuild the mirrors.

I also understand that this whole procedure might not work and then I'll have to start over, so to speak.

Thanks for your help. Tim

It may not work only because we were not able to solve all the issues converting Apple RAID disks with multiple partitions on them (and are out of sync/missing disks). Let us know if you were able to do this the simple way. ;-)

Here's a follow-up to let you know about the happy ending to this RAID rebuild story. After developing a detailed game plan with you, I came up with a different game plan that I knew would have a likelihood of success, which was an important consideration since I needed to get this production server back into production.

I booted the Mac mini from an USB flash drive running OS X 10.10. I then used Apple's Disk Utility to add the new internal SATA drive to the degraded RAID and let Disk Utility repair the RAID. This worked. Both partitions (bootmirror and datamirror) were rebuilt successfully and I could put the mini back into production. Now, on some quiet afternoon, I"ll boot the mini off of a USB flash drive running OS X 10.11 and SoftRAID and convert the healthy mirror into a SoftRAID mirror.

Let me know what follow-up questions you have. Thanks.

Great!

When you convert to SoftRAID, do a validate volume.