What now?
Well, forget Part 7 (fortunately). The SSD-Raid is working fine! It always assembled itself after several reboots. That’s good news, I guess!
In the meanwhile I fucked up again. I ordered an external USB-casing without a disk recently. While trying to get it up and running, I accidentally disconnected the USB-thingy connected to my external drives from power. Since then the kernel complains about the 2.5″ USB drive without power supply, but I got it up and running again.
Right now I’m copying all data from that drive to a member of the failed HGST-Array. Hopefully it’s not the failed drive, but we’ll see…
Creating a physical volume with pvcreate didn’t work out of the box. The command bailed out saying that it couldn’t open the device exclusively. At first I thought that it was because of the pre-existing PV-Signature, so I zeroed out the first GB, but that didn’t help, either. Check-MK came to help, telling me that md127 was in a degraded state.
Of course! The drive contained a RAID-Superblock, so the kernel tried to start the the RAID, but couldn’t. Nevertheless, that kept the drive busy. Stopping it with
# mdadm -S /dev/md127
should have helped, I guess…
Anyway, wrote 1.1TB to the drive without errors. So, chances are that it isn’t the defective drive.