Troubleshooting Promise Pegasus Thunderbolt RAID

We have a client that does quite a bit of production work. They have a very robust Promise RAID setup (2 x R4 and 1x R6) with over 30TBs of storage. We recently ran into an issue with the drives in the R6 showing up as Dead/Offline. After some back and forth with Promise tech support and conducting our own research we found a rather simple solution. I wanted to document our solution in an effort to save you some time if you encounter this issue. 

After a rather serious Florida Summertime storm all the drives on an R6 were showing up offline.  Being that this was setup as a RAID 5 this posed some potential data loss. Thankfully, this RAID was the clients versioned backup so worse case we replace the drives and reclone from the working RAID. I still found it highly suspect that 6 drives would have failed so I ran a subsystem report and sent it off to Promise's tech support. Within an hour I receive a response recommending that we upgrade the firmware and see if that resolves the issue. We proceeded to upgrade the firmware on the R6 by doing the following:

Click on Promise utility on the Menu Bar -> Check for updates. - It would prompt for updating the firmware, update the firmware. - After the update, click on subsystem information on the Promise Utility window -> Shutdown/Reboot. - Choose reboot & restart the unit.

After the unit rebooted the drives were still showing offline. I then started to do a bit more research and come to find out that others have experienced the logical drive of the Promise RAID going offline after abruptly losing power. The issue was resolved by forcing the drives back online. Unfortunately, the option to force the drives online isn't available through the Promise Utility GUI but has to be done via the Terminal application. See below for instructions on forcing the drives back online.

On the Mac, open the Terminal app and run:

promiseutil

This will open the Promise Utility. Now type the following:

phydrv -a online -p 1 

phydrv -a online -p 2

phydrv -a online -p 3

phydrv -a online -p 4

If you have the R6 you will need to add the following commands in order to force drives 5 & 6 online -

phydrv -a online -p 5

phydrv -a online -p 6

After you force the drives online reboot the RAID and you should be good to go.