Ds8000 Hardware Specifics; Storage Unit Structure - IBM DS8000 User Manual

DS8000 hardware specifics

The DS8000 models offer a high degree of availability and performance through
the use of redundant components that can be replaced while the system is
operating. You can use the DS8000 models with a mix of different operating
systems and clustered and nonclustered variants of the same operating systems.
Contributing to the high degree of availability and reliability are the structure of
the DS8000 storage unit, the host systems it supports, and its processor memory
and processor speeds.

Storage unit structure

The design of the storage unit, which contains the base model and the expansion
models, contributes to the high degree of availability that is associated with the
DS8000. The primary components that support high availability within the storage
unit are the storage server, the processor complex, and the rack power control card.
The storage unit also has redundant fibre switches, with fibre fabric connections to
both processor complexes. The entire power system at all levels is fully redundant.
There are redundant private LAN networks between each storage unit and the
management consoles (even if there is only one management console).
Storage unit
Storage server
Processor complex
Rack power control card
Multi-path subsystem device driver
A storage unit consists of a storage server and two or more storage (disk)
enclosures that are packaged in one or more racks with associated power
supplies, batteries, and cooling.
A storage server consists of two processor complexes, four or more I/O
enclosures, and a pair of rack power control cards.
A processor complex controls and manages the storage unit to perform the
function of the storage server. The two processor complexes form a
redundant pair such that if either processor complex fails, the remaining
processor complex performs all storage server functions.
A redundant pair of rack power control (RPC) cards coordinate the power
management within the storage unit. The RPC cards are attached to the
service processors in each processor complex, the primary power supplies
in each rack, and indirectly to the fan/sense cards and storage enclosures
in each rack.
The IBM System Storage Multi-path subsystem device driver (SDD)
provides load balancing and enhanced data availability capability in
configurations with more than one I/O path between the host server and
the DS8000 series system. Load balancing can help reduce or eliminate I/O
bottlenecks that occur when many I/O operations are directed to common
devices that are using the same I/O path. The SDD also helps eliminate a
potential single point of failure by automatically rerouting I/O operations
when a path failure occurs, thereby supporting enhanced data availability
capability.
Chapter 1. Introduction to IBM System Storage DS8000 series
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