Ficon/Zhpf And Escon Host Attachment; Ficon/Zhpf And Escon For Zseries Hosts; Setting Up Escon And Ficon/Zhpf Links; Multi-Pathing For Escon And Ficon/Zhpf - HP XP20000/XP24000 Operation Manual

2 FICON/zHPF and ESCON host attachment

This chapter describes and provides general instructions for attaching the storage system to a mainframe
host using a FICON/zHPF or ESCON CHA.
For details on FICON/zHPF connectivity, FICON/Open intermix configurations, and supported HBAs,
switches, and directors, contact your HP representative.

FICON/zHPF and ESCON for zSeries hosts

This section describes some things you should consider before you configure your system with
FICON/zHPF or ESCON adapters for zSeries hosts.

Setting up ESCON and FICON/zHPF links

If the system requires x ESCON links, where x is the number of links to receive the performance and
availability attributes that you want, you must consider the number of FICON/zHPF links that you
need.
For example, you can map four ESCON links to a single FICON/zHPF link and maintain approximately
equivalent performance. If the ESCON channel use is low, you can map six or eight ESCON links to
a single FICON/zHPF link. If the ESCON channel use is high, you can map two ESCON links to a
single FICON/zHPF link.

Multi-pathing for ESCON and FICON/zHPF

Consider the difference between the path groups when you compare FICON/zHPF to ESCON.
For example, for ESCON, you can configure four or eight paths per path group from a host to a
storage unit.
For ESCON, you can configure at least four paths in the path group to maximize performance. Most
ESCON controllers initiate channel command execution that partially synchronizes the lower disk
drive interface with the upper channel interface. This channel command allows you only a very short
time to reconnect. The consequence of limited time is a reconnection that can fail. Having eight paths
in the path group minimizes the number of missed reconnections. Increasing the number of path
groups does not minimize the number of missed reconnections substantially. If you use eight paths in
path groups, you can increase the overall throughput.
For FICON/zHPF controllers, there is no synchronization between the lower disk drive interface and
the upper channel interface. The number of paths in the path group depends on the throughput
requirement. If it takes x paths to satisfy the throughput requirement, where x is the number of paths
(minimum of two paths, maximum of eight paths), set the path group to x.

Attaching ESCON CHAs

You can attach the XP disk array to a host system using ESCON adapters. The storage system can
be configured with up to 96 ESCON physical channel interfaces.
XP Disk Array Mainframe Host Attachment and Operations Guide 11