[Modified3019]

In my case, the drive suddenly only shows having 1GB of read only space available. The firmware version will be reported as “ERRORMOD” (meaning, error mode). There are no warning signs, it just happens.

All data is lost the moment you see ERRORMOD, there is no recovery of data that I am aware of. It is sometimes possible to clear the drive and recover function for the now untrustworthy drive: https://forums.servethehome.com/index.php?threads/pm9a3-firm...

It’s not the only way a drive can fail, but it’s the most immediately obvious one.

Other ways of the firmware failing result in no drive showing up at all, or data corruption. Physical failures can also happen, like breakage of the solder balls under the chips (which fixable enough to get data off it).