I recently expanded a raid-1 to a raid-6 with six drives. I ordered all four of the new drives from the same place, and all of them were advertised to be the same drives as the original two--Seagate 15krpm 146gb.
However, when I was looking at the drives in the perc6/i utility, one of them appeared to be an earlier firmware version; it had S515, compared to the other five drives with S527. Sure enough, after inspecting the drive itself, the label advertised the earlier firmware version. Running Dell's SAS firmware upgrade utility should have in theory moved them all up to S52A, but when I ran it it moved the S527 drives up to S52A, and left the S515 drive untouched.
Is this something to be worried about? If it's something that should be corrected, is there a way to target a particular drive for upgrade since the firmware utility didn't seem to do it by itself?
From my experience in dealing with Dell's support robots, they will not talk to you unless you have the latest firmware. they send you a link and tell you call them back when you are done updating.
While Dell may tell you you can't run it mismatched, and it may not be the "best practice", at my old job we ran mismatched firmware pretty much on every single drive, and the failure rate was exactly the same, despite the new firmware versions.