G'day All,
I thought I might share an experience we just had with updating 4x Seagate 1TB ES.2's from SN04 to AN05 in a "Live" RAID 10.

We have done, perhaps 5 arrays and about 30 disks, and it has always worked fine except for the this one. (Of course we backed up the data etc before each update but who wants to restore 1TB of data?).

The Firmware update worked fine, by simply placing the drives on the MB controller and booting with the supplied ISO.
However after the firmware update, 3 of the drives in the RAID 10 lost their metadata, so the array was offline.
It turns out that because the Seagate firmware can change the drive "size" and the Adaptec RAID metadata (the bit that describes the drive and it's function in the array).
So in this case the fix was to get into the card BIOS and first initialize all of the drives, then recreate the array with the EXACT SAME drives involved but not "init" the array.
This is the crucial part.
"Initializing" the drives(separate menu option and it falsely warns you in this case that you will lose data), makes sure the Metadata is cleared.
But "Build / Verify", "Clear" and "Quick Init" in the build array menu, is the one that wipes your data!
Adaptec desc of the build modes.
So only via the BIOS do you get the option to build the array without doing one of the above. (It think it was "Build without init").
Then, so long as you have the same drives selected as part of your array and they are on the same controller ports (we made the mistake of changing cables at one point), your data will magically appear. Then make sure you run a Verify/Fix and you are good to go.

I would like to publicly thank the Australian Adaptec tech for his help guiding us through this.
While the basic procedure is listed in the Adaptec ASM software help, it implies you can do it with the GUI. You cant.... The BIOS menu is the only one with the build without init.

Hope this saves someone else a bit of heartache.

Rgds Ben