Back-End Directors And Array Domains - Hitachi Universal Storage Platform V Reference Manual

Back-End Directors and Array Domains

The back-end director (BED) features control the transfer of data between the
data drives and cache. The BEDs are installed in pairs for redundancy and
performance. The USP V can be configured with up to eight BED pairs,
providing up to 64 concurrent data transfers to and from the data drives. The
USP VM is configured with one BED pair, which provides eight concurrent data
transfers to and from the data drives. The USP V/VM supports two types of
BED features, standard and encrypting. The encrypting BED (EBED) provides
data encryption for both open and mainframe systems.
The data drives are connected to the BED pairs by fibre cables using an
arbitrated-loop (FC-AL) topology. Each BED pair has eight independent fibre
back-end paths controlled by eight back-end microprocessors. Each dual-
ported fibre-channel drive is connected through its two ports to each board in
a BED pair over separate physical paths (loop switch in between the drives and
ports) for improved performance as well as redundancy.
Table 2-2
(one per fibre path) that support data transfer to and from cache. Each dual-
ported drive can transfer data over either port. Each of the two paths shared
by the drive is connected to a separate board in the BED pair to provide
alternate path capability. Each BED pair is capable of eight simultaneous data
transfers to or from the data drives.
Table 2-2
Number of back-end director features
Types of back-end director features
Back-end paths per BED feature
Back-end paths per storage system
Back-end array interface type
Back-end interface transfer rate (burst rate)
Maximum concurrent back-end operations per BED feature
Maximum concurrent back-end operations per storage system
Back-end (data) bandwidth
Hitachi Universal Storage Platform V/VM User and Reference Guide
lists the BED specifications. Each BED pair contains eight buffers
BED Specifications
Parameter
Architecture and Components
Specifications
USP V: 1 – 8
USP VM: 1
Standard
Encrypting
8
USP V: 8 – 64
USP VM: 8
Fibre-channel arbitrated loop (FC-AL)
400 MB/sec (4 Gbps)
8
USP V: 64
USP VM: 8
USP V: 68 GB/sec
USP VM: 8.5 GB/sec
2-9