Anyone who has recently purchased Western Digital's Caviar 160, 250, 400 and 500GB SATA II drives, may need to download a firmware update.
Western Digital quietly issued a firmware update on its web site that should be applied to the company's WDxxxxYS series of "Caviar SE16" SATA2 drives. Apparently, there was serious problem with the disks with a conflict between a feature of the drives' firmware and some RAID controllers.
As a result of this miscommunication, the RAID adapters incorrectly identified the disk as dead, thus disappearing suddenly and without real cause from the RAID array. Western Digital had this to say about the affliction:
...an issue where a WD1600YS, WD2500YS, WD4000YS, or WD5000YS hard drive is dropped from a RAID set without reporting errors after a period of normal usage.
The fix updates the firmware code in the affected drives to version 20.06C06 on the WD1600YS and WD2500YS models, and version 09.02E09 on the WD4000YS and WD5000YS.