I have a RAID configured Mac Mini Server. The latest version of OS X won't run on a RAID machine. So how do I deconfigure the Mini? I have it backed up via Time Machine.
MAC MINI SERVER (LATE 2012), OS X Mavericks (10.9.2)
If the array is erased then you cannot install macOS on it. If Macintosh HD is grayed out that may well be because it already is a High Sierra startup volume. I don't yet know what the deal is about your array, but if you have a working system on Macintosh HD that is the Server, then it cannot be upgraded using the Client installer. Eventually, I'm going to suggest that you get a working system on Macintosh HD and upgrade it to High Sierra if needed. Then clone Macintosh HD to your array or use Time Machine to backup Macintosh HD to the array or some other backup software - I recommend getting Carbon Copy Cloner.
I infer from your comments that you think I'm dealing with some sort of external RAID array. That is not the case. I'm referring to a Mac Mini Server with two HDs, currently not running as a server. The two internal HDs constitute a RAID0 (Mirror) setup. I have had no problem in the past upgrading this machine to the latest OS X version -- until this one. The internal array is not erased, otherwise the machine would not boot, no? It is running OS 10.12.6 while my other Macs are running 10.13.3. What subtlety am I missing here?
Now we are at last back to my original question: "The latest version of OS X won't run on a RAID machine. So how do I deconfigure the Mini?" That is, in Kappy's words,how do I break the RAID and designate one drive as the startup drive?
Yes, the display is similar to your Disk Utility example except each HD in the RAID array takes up all the available space although the overall system depicted as Macintosh HD shows lots of free space since that depicts the actual content rather than ownership. As I noted in my previous post the error message is: Can't unmount RAID set 1F8..... to delete it.
Since the RAID set essentially commandeers the entire logical disk space I can't delete or unmount it. As this comprises all the disks available to the Mac Mini there is no other drive from which to boot it. Catch 22! Nice work, Apple. Linux is easier to deal with.
I had already tried to break up the array and got the same failure message: Can't unmount RAID set 1F8..... to delete it. Using Preferences to select a target disk simply points to Macintosh HD. Catch 22 again.
The only drives available to this Mac Mini are the two internal ones, 1 TB each. There are no "different drives" at least not physical ones -- unless I load Sierra onto a flash drive. Will a mini boot from a flash drive?
Looks promising but Delete RAID fails because: Can't unmount RAID set . . . . to delete it.
Screen shots:
What is below the array's Desktop icon? The Desktop icon and the array's name are together. Installation is to that, not one of the array members. There is no such thing as one of the members being the startup disk. I suggest you try the command: diskutil ar list. You will see the array's Name at the top of the information along with the Device Node. This will list your AppleRAID.
I don't know what the Desktop name of the array is but that is the disk you want for the installer.
How do I de-RAID a Mac Mini?
