I had a RAID 5 array with (3) Seagate ST336752LC drives. Firmware version 0002 on the original drives. The RAID controller shows them having 34941MB each.
One drive failed, so I ordered another ST336752LC drive. This one has a *newer* firmware and measures up a whopping 200MB *smaller* than the original drives.
This is preventing the RAID BIOS from adding the new drive to the array.
The known defect list is about 3 times larger (1100, as opposed to 200 - 400 on the other drives), but even a variation of 200 defects between the other drives doesn't change the drive size by even 1MB.
This is an older server.