Choosing the Right Disk Technology in a High Availability Environment DRAFT Version 2.0, August 1996

DRAFT -- Revision 2.0
August 22, 1996Page 27
+ automatic AutoRAID controller failover with HP-UX Revision 10.0
+ performance approaches that of JBODs/HASS at lower cost
- no control over the placement of data for application performance tuning
- overall performance depends entirely on workload and amount of RAID 1
space configured
- no boot support in a multi-initiator (shared bus) environment
- UPSs required for powerfail support
Symmetrix 3000 Series Integrated Cache Disk Arrays (ICDA)
HP resells the Symmetrix 3000 Series Integrated Cache Disk Arrays manufactured by
EMC Corporation, henceforth called Symmetrix for brevity. Many configurations are
available, with product numbers in the S11xxA and S12xxA ranges. These arrays have
the following features:
combines RAID 1 and RAID S (a special case of RAID 5) in the same array
capability for remote placement of mirrored unit on campus or inter-city with
the Symmetrix Remote Data Facility (SRDF)
on-line replacement of failed disk modules
up to 8 redundant active controllers with automatic failover
up to 4 GB cache
redundant fans
redundant power supply
on-line replacement of controllers, fans and power supplies
connection to up to 16 different host systems with up to 32 SCSI ports
Capacity and the features listed above make the Symmetrix the practical choice in
many situations where hundreds of Gigabytes up to multiple Terabytes of storage is
required and where multi-system connectivity and performance are critical factors.
Installation, configuration and support is provided for Symmetrix directly from EMC
Corporation.
Symmetrix units are external, standalone units that must be powered separately. They
contain enough battery capacity to totally flush the cache in case of power failure.
Disk storage is assigned to a SCSI LUN according to desired capacity. LUNs are
configured by EMC according to application needs and then assigned for access by one
or more of the external SCSI ports, thus allowing multiple system access to the same
SCSI LUNs, if desired. Arbitration such as that available with MC/ServiceGuard and
MC/LockManager must be done among the systems so that multiple systems do not
modify the same data at the same time.