Encrypting issue, laptop restarting all the time

I started an Encryption process on my 12TB RAID 1 LaCie 2Big (APFS) a few days ago. The drive contained 2.5TB data.

The laptop was crashing and restarting several times. Then I plugged the drive into my iMac 2011. The iMac is not restarting, but the process is extremely slow. It seems I would need weeks or months to finish. Since that I have deleted 2TB data, only 500GB left (the most important ones), but the process didn’t speed up. I’m trying to copy the data to another drive, but it shows that many files are corrupted; therefore I can’t even copy the files to another drive.

Can anybody give advice what to do? I would like to copy the data to another drive and to try to format the LaCie 2 Big, though I don’t know is it possible while this never-ending encryption is ongoing.

I’m on a late 2016 MBP, running High Sierra. Many thanks!

The encryption process speed varies, and it can take a day per TB.

Just let it run all the time (overnight included)

There is not much you can do to sped it up.