G'day Barrday,
We have just started getting an error that I wonder if it is related.
The scenario is a we have a single Adaptec 5405 card in a Intel SSR212MC2, which has the onboard controller disabled, and 12x Seagate ES.2 1TB drives installed.

The firmware and Bios on the card are 5.2.0 while DSS is 5.0.DB47000000.3178 and the "Driver" is reported as 1.1.5 (2455). Drives are Seagate ES.2 1TB with the "Raid" AN05 firmware.
(But the current Linux driver on the Adaptec site is 1.1.5 (2459)? is this an issue?)

We have had numerous errors and faults with the arrays on the controller and not able to make them "Optimal". The current configuration is all 12 in a Raid6 Array, when the array controller was told to "Verify and Fix" it got to 15% and then sent an alert:
Event Description: Build/Verify failed: controller 1, logical device 1 ("array0") [0x00].
When we investigate further the Agent log states that the drive in Slot 8 has been removed. Which is clearly not the case, after a "rescan" Slot 8's drive returns and it is now "rebuilding" it.
So does this sound like the same issue you are having?
I can't figure out why the controller thinks a drive has been "removed".... to me that is a drive failure, but so far we have lost Slot 11,10,9 and 8, so I doubt it as a true error.

BTW, unrelated we also had the error when we tried to create an iSCSI VMFS, until we created a FS on it first, THEN went and created the VMFS, worked like a charm after that.

So, anyone else using the Adaptec 5805 and finding issues?

Rgds Ben.