Hitachi has just introduced a new disk drive for its 99x0
subsystems. The drive is a 72 gig Hitachi disk with an
identifier of DKR2DJ72FC. This infodoc documents the correct
deployment of this drive into a 99x0 array.

   There are now 2 different 72 gig Hitachi Drive types.
The identifiers are.

                DKR1CJ72FC -> Existing 72 gig drive type.
                DKR2DJ72FC -> New 72 gig drive type.

  Release of the drives included the following qualification
statements.

            a. The drive types are compatible.
            b. They can be intermixed within the same 99x0.
            c. They can be intermixed within a single parity group.
            d. No microcode upgrade is necessary.

However, the following rules apply when intermixing disks.

            a. DKR1CJ72FC may be identified with EITHER number.
               (DKR1CJ72FC can be DKR1CJ72FC or DKR2DJ72FC)
            b. DKR2DJ72FC MUST be idenftified as DKR2DJ72FC.

 Example: Its perfectly safe to replace a failed DKR1CJ72FC with a
          DKR2DJ72FC disk providing it is identified as such during
          replacement.
 Example: During a Define and Install, DKR2DJ72FC disks MUST be
          identified as DKR2DJ72FC disks.
 Example: Do NOT identify a DKR2DJ72FC as a DKR1CJ72FC. 
            

Information was gathered from restricted internal Hitachi 
ECN 410I-H026. The document is titled
  "Introduction of Compatible HDD with New Technology"
Since this document is not available for our eyes, this 
infodoc has been generated.