Time Machine restore stuck on “Preparing ” for more than 24 hours, how can I diagnose the nature of the problem? Recently I got myself into quite a pickle that eventually required I format my Mac’s dual-SSD RAID-0 array and restore from a Time Machine backup.

Unfortunately Time Machine has spent the past 24 hours stuck on “Preparing [destination disk]” and shows absolutely no sign of progress. (The backup is hosted on a Time Capsule-emulating Synology NAS.) There is no information on what is going on behind the scenes, just a solid pulsing blue progress bar that doesn’t even initialize and start creeping rightwards. Before the process began there was some cryptic remark about encryption needing to be disabled subsequently re-enabled as FileVault once restoring is complete, and I authorized the request to erase the destination disk.

Quite suspiciously it asks me to acknowledge disabling encryption every time I restart the process, which might imply that some latent form of FileVault is lingering, but I have erased the disk several times and each time explicitly instructed the system to format as JHFS+, unencrypted and case-insensitive. 

(Keep in mind that “disk” in this context actually means RAID volume, as the two physical SSDs each host slices of the unified striped RAID-0 volume.)

I tried dropping into the Terminal because I vaguely remember the 

tmutil


commmand but it is not present in the barebones toolkit of the macOS installer.

Can somebody help me figure out what is going on?

Thanks.

(Tragic aside: while in a panic and desperately trying to unmake my unbootable APFS-formatted RAID array which I created and that got me into this pickle, I accidentally nuked my FireWire-attached CarbonCopyCloner backup, so I’m stuck using Apple’s blunt instrument with no information whatsoever.)
I have since discovered that Apple has fully deprecated support for the APFS and that consequentially restoring from a network-attached device (as is my Synology NAS) requires re-sharing with the SMB protocol.