So we powered it down for a move, and on power up the RAID configuration has disappeared. The disks, controllers, etc all look OK, just no RAID so no boot.
The suggestion is that it's possible to rebuild the RAID configuration without losing data. Any ideas how? [It seems to be RAID-1 btw]
The RAID is ServerRAID-C100 by LSI. Can see all ths disks on pre-boot, but all . What to do?
Running Windows Server, if it matters.
Shortly after this we used the BIOS to reenter a best guess RAID configuration
and it just worked. The system booted, Windows re-appeared and it was as if nothing had ever happened.
In the past year, while still trying to solve the problem permanently, we've repeated this process to recover from power fail some 3 times. This is called living dangerously. We still don't have a good answer why.
Best Answer
First, try to find out why this happened. It could be that your RAID battery is dead and your configuration is stored only in a CMOS. That would be an unfortunate reality.
This problem is likely correctable. I would say that if you want to recover the data on those disks without having to revert to a previous backup, you should make 1:1 disk image copies of them before doing anything that could alter their contents.
Finally, if you're certain that this was a RAID 1 between two disks, then you can create a new RAID 1 using the same disks, opting to not initialize the array. This will create the abstraction but not write anything to the disk. If this was truly an issue with your metadata being lost, you should be good to go after that.
Beyond that, it's difficult to offer recommendations for you with the data given. If these basic steps don't cut it for you, it may be time to turn to a professional.