There are three disks in the system. sda = internal hard drive, sdb = backup USB, sdc = plex USB.
The hard drive is the only one that is marked as bootable. It hangs on the backup USB and not the plex USB.
It still hangs if I disable all but the hard drive for booting.
root@orca:/home/mark# fdisk -l /dev/sda
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x00043575
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1920129023 1920126976 915.6G 83 Linux
/dev/sda2 1920131070 1953523711 33392642 15.9G 5 Extended
/dev/sda5 1920131072 1953523711 33392640 15.9G 82 Linux swap / Solaris
Partition 2 does not start on physical sector boundary.
root@orca:/home/mark# fdisk -l /dev/sdb
Disk /dev/sdb: 2.7 TiB, 3000558944256 bytes, 732558336 sectors
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x00028375
Device Boot Start End Sectors Size Id Type
/dev/sdb1 256 732558335 732558080 2.7T 83 Linux
root@orca:/home/mark# fdisk -l /dev/sdc
Disk /dev/sdc: 1.8 TiB, 2000365289472 bytes, 3906963456 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x48f9a2e9
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 3906963455 3906961408 1.8T 7 HPFS/NTFS/exFAT
root@orca:/home/mark#
Mark