Browse Prior Art Database

Concurrent Maintenance Direct Access Storage Device for Computer Systems

IP.com Disclosure Number: IPCOM000112230D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-27

Publishing Venue

IBM

Related People

Dimmick, RF: AUTHOR [+4]

Abstract

Disclosed is a method for providing individually removable Direct Access Storage Device (DASD) drives when those drives are mounted in a dual DASD package or container. The design provides for individual device removal with the system under power and performing customer operations (concurrent maintenance).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 15% of the total text.

Concurrent Maintenance Direct Access Storage Device for Computer
Systems

      Disclosed is a method for providing individually removable
Direct Access Storage Device (DASD) drives when those drives are
mounted in a dual DASD package or container.  The design provides for
individual device removal with the system under power and performing
customer operations (concurrent maintenance).

      The design presented here describes a dual-DASD package that is
equivalent in exterior form to the standard dual-DASD mounting used
in the IBM AS/400* Model 9404 and similar computing systems, but
where each individual DASD drive docks to and is individually
removable and, thus concurrently maintainable, from the package (or
"sleeve") with the the "sleeve" itself docking to the system in a
similar manner to the "shoebox" of the original design.

      Additionally, the power regulator in the original design is
duplicated such that each drive receives regulated power from an
individual regulator; those regulators are in turn mounted with their
drives and are removable with them, allowing the regulators
themselves to be concurrently maintained.

      The design point also includes a method for shutting down
(quiescing) the data busses the drives are connected to to ensure no
data is lost during the remove/install cycle.  Drives are attached to
common busses which must be protected from electrical noise that may
be introduced when a drive is plugged or unplugged.  Deactivating a
bus shuts down all drives attached to that bus.  A mechanism is also
provided to reactivate the bus after a remove/replace operation is
complete.  The bus quiesce system allows a drive to be removed from a
bus with a minimum of apparent "downtime" to the user or data
corruption.  The specific logic functions and architecture/design
used to accomplish the bus quiesce are not described in detail,
however the activation mechanism will be discussed here.

      Redundant Array of Independent DASD (RAID) or drive mirroring
is a prerequisite for the use of concurrent maintenance hardware in
the 9404 and similar systems using a dual-DASD package.

HARDWARE MECHANICAL DESIGN

1.  DRIVE TRAYS (Figs. 1 and 2)

    o   DASD drive (1) is mounted to a sheet metal carrier plate (20)
        which is equipped with vertical sheet metal divider (21) to
        which is attached power regulator (4).  Carrier plate (20)
        also contains connector flange (22), to which connector (B)
        of SCSI bus cable (23) is attached (connector (A) of cable
        (23) plugs directly to DASD drive (1)).  The mounting of
        connector (B), on cable (23), is accomplished by trapping
        flange (22) between connector (B) and tapered alignment pins
        (24) which are screwed to the connector.  The interface
        between connector (B), flange (22) and pins (24) is designed
        to allow conn...