Since nov. 16 in 2017 I have experienced 5 instances of this, labelled "Minor". Unit gives of some irregular beeps then seems to continue, but unit is not found by promise utility and connection to my iMac 27"-5K seems lost. On rebooting iMac the (3 logical) drives are gone! Still unit shows blue led for drives. Yet the poverswitch is not blue! pressing the switch to power it down is nonresponsive. only way to get unit back is to remove powercord, wait and then replug it. Very inconvenient and not very promissing for future. I use drive for backup and timemachine. my Live data is at a separate Pegasus2 R4, which works ok.
the last 2 times this happened it was PD 2 that caused it. I am worried that the system has an internal controller error, since only removing the power will return it to 'working' condition.
Mediapatrol has not found any error on disks.
please advise if/how I can test further
kind regards
Palle Jensen