The ls command does not find anything, and with the other evidence, it seems reasonable to say it is BIOS legacy.
decided to try dd on the suspect disk
have never used dd before
sudo mount /dev/sdb1 /mnt
dd if=/dev/zero of=zero bs=1024k count=1024
dd: failed to open 'zero': Permission denied
# don't know why permission denied
sudo dd if=/dev/zero of=zero bs=1024k count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1,0 GiB) copied, 35.9016 s, 29.9 MB/s
That all looks like good news for the partitioning of the disk, but not sure why permission denied…
Carried on today with an attempt to copy the working disk to the suspect disk using dd with the suspect disk attached via usb docking station.
sudo dd if=/dev/sda of=/dev/sdb
Not sure if sudo dd if=/dev/sda/sda1 of=/dev/sdb/sdb1 should have been used. It has been running for about 8 hours and should finish in the next 2. I found the “status=progress” option could have been added, but in the meantime, have used “sudo pkill -usr1 dd” to request a status from the dd command.
If this works, should it be possible to do a usb boot from the suspect disk?
This old R61 and the two disks are for experimenting and learning.
I am open to suggestions and will certainly want to try out ddrescue, testdisk and dcfldd which came up during research, and also creating an endeavouros on the suspect disk via usb if possible, because that would be a useful thing to be able to do.
Hope that makes sense.
p.s. wanted to check understanding on dd - the up side to dd is that it just writes blocks to the disk, so partitioning table, and any partitions, to mirror the input, but the downside is that everything gets copied even if it is “empty” space. Presumably there isn’t a magic option that only copies the good stuff…