Front-End Directors And Host Channels - Hitachi Universal Storage Platform V Reference Manual

Front-End Directors and Host Channels

The Universal Storage Platform V and VM support all-mainframe, all-open-
system, and multiplatform configurations. The front-end directors (FEDs)
process the channel commands from the hosts and manage host access to
cache. In the mainframe environment, the front-end directors perform CKD-
to-FBA and FBA-to-CKD conversion for the data in cache.
Each front-end director feature (pair of boards) is composed of one type of
host channel interface: fibre-channel, FICON, or Extended Serial Adapter
(ExSA) (compatible with ESCON protocol). The channel interfaces on each
board can transfer data simultaneously and independently.
The FICON and fibre-channel FED features are available in shortwave
(multimode) and longwave (single mode) versions. When configured with
shortwave features, the USP V/VM can be located up to 500 meters (2750
feet) from the host. When configured with longwave features, the USP V/VM
can be located up to ten kilometers from the host(s).
•
FICON. The FICON features provide data transfer speeds of up to 4 Gbps
and have 8 ports per feature (pair of boards). The same FICON features
(boards) are used for FICON and High Performance FICON (zHPF).
FICON/zHPF uses a mapping layer technique based on fibre-channel and
multiplexing technologies to improve data-transfer rates, reduce the
number of channel connections, and support greater distances between
Hitachi USP V/VM systems and mainframe hosts. FICON and FICON/zHPF
have identical hardware specifications, but FICON/zHPF offers improved
performance.
FICON data transmission rates vary according to configuration. For further
information on FICON connectivity, refer to the Mainframe Host Attachment
and Operations Guide (MK-96RD645), or contact your Hitachi Data
Systems representative.
•
ESCON. The ExSA features provide data transfer speeds of up to 17
MB/sec and have 8 ports per feature (pair of boards). Each ExSA channel
can be directly connected to a CHPID or a serial channel director. Shared
serial channels can be used for dynamic path switching. The USP V/VM also
supports the ESCON Extended Distance Feature (XDF).
•
Fibre-Channel. The fibre-channel features provide data transfer speeds of
up to 4 Gbps and can have either 8 or 16 ports per feature (pair of
boards). The USP V/VM supports shortwave (multimode) and longwave
(single-mode) versions of fibre-channel ports on the same adapter board.
Fiber-channel connectivity is also supported for IBM mainframe attachment
when host FICON channel paths are defined to operate in fiber-channel
protocol (FCP) mode.
Table 2-1
and specifies the number of channel connections for each configuration.
Hitachi Universal Storage Platform V/VM User and Reference Guide
lists the specifications and configurations for the front-end directors
Architecture and Components 2-7