HP StorageWorks XP Disk Array Mainframe Host Attachment and Operations Guide XP24000, XP20000 (A5951 - 96151, September 2007)

NOTE:
ESCON host channels limit the number of devices per channel to 1024. To fully access 4096 devices on
a storage unit, it is necessary to connect a minimum of four ESCON host channels to the storage unit. You
can access the devices through a switch to a single storage unit ESCON port. This method exposes four
control-unit images (1024 devices) to each host channel.
The storage unit supports the following operating systems for S/390 and zSeries hosts:
• z/OS
• z/VM
• Transaction Processing Facility (TPF)
• Virtual Storage Extended/Enterprise Storage Architecture (VSE/ESA)
• Linux
ESCON connectivity on zSeries hosts
This describes how to attach a storage unit with ESCON adapters.
XP disk array storage units can be attached through ESCON links to different central-electronic
complexes and logical partitions (LPARs).
For optimum availability, you can make the ESCON host adapters available through all bays and
spread the connections to any single host across both clusters. For optimum performance, you can
have at least eight host adapter ports installed on four ESCON host adapter cards in the storage unit.
This setup ensures the best performance from the attached systems.
Host adapters, cables, distances, and specifications for ESCON adapters on zSeries hosts
A storage unit emulates 0 through 16 of the logical controllers. The logical controllers are typically
split between 2 clusters. Because the ESCON adapter connects to both clusters, each adapter can
address 16 logical controllers.
Each ESCON host adapter provides two host connections. This requires two ESCON cables for each
adapter for S/390 and zSeries hosts. The maximum standard distance for ESCON cables is 2 km
(1.2 mi) with 50-µm multimode fibre and 3 km (1.9 mi) with 62.5-µm multimode fibre. This distance
can be extended 103 km (64 mi).
NOTE:
For optimum performance, use a cable shorter than 103 km (64 mi). An ESCON host channel can connect
to more than one storage unit port through an ESCON director.
The S/390 or zSeries host system attaches to one port of an ESCON host adapter in the storage unit.
Each storage unit adapter card has two ports. For the XP24000/XP20000 disk array, each ExSA
has 4 ports per adapter card and 8 per pair.
Cable lengths and types for ESCON adapters on zSeries hosts
The cable that is attached to the host adapter can be up to 2 km (1.24 mi) in length using 50-µm fibre
or 3 km (1.86 mi) in length for 62.5-µm fibre. This cable is used to make the connection between the
following components:
XP Disk Array Mainframe Host Attachment and Operations Guide 23