User`s guide

4 Implementing an Open IBM SAN
1.1.3 LUN affinity
For Fibre Channel attachment, LUNs have an affinity to the host's Fibre Channel
adapter through the world-wide port name (WWPN) for the host adapter. In a
switched fabric configuration, a single Fibre Channel host could have physical
access to multiple Fibre Channel ports on the ESS. In this case, you can
configure the ESS to allow the host to use either:
򐂰 All physically accessible Fibre Channel ports on the ESS
򐂰 Only a subset of the physically accessible Fibre Channel ports on the ESS
In either case, the set of LUNs that are accessed by the Fibre Channel host are
the same on each of the ESS ports that can be used by that host.
1.1.4 Targets and LUNs
For Fibre Channel attachment, each Fibre Channel host adapter can
architecturally attach up to 256 LUNs. The ESS supports only a maximum of
4096 LUNs divided into a maximum of 16 logical subsystems each with up to 256
LUNs. If the software in the Fibre Channel host supports the SCSI command
Report LUNs, then you can configure all 4096 LUNs on the ESS to be accessible
by that host. Otherwise, you can configure no more than 256 of the LUNs in the
ESS to be accessible by that host.
1.2 Attaching an ESS to a FICON channel
This topic tells you how to configure the IBM Enterprise Storage Server for
FICON attachment.
1.2.1 Configuring the ESS for FICON attachment
You can perform a FICON channel attachment on the IBM 2105 Model F10 and
F20. You cannot perform a FICON channel attachment on the IBM 2105 Model
E10 and E20. When you attach an F10 or F20 to a FICON interface, you must
use the following host adapter feature codes:
򐂰 Feature code 3021 — This is a long wave laser adapter that includes a 31-m
(100-ft) 50-micron cable with duplex connectors. Because the 3021 uses one
of four slots in one of the four I/O bays, you can have a maximum of 16
adapters in the ESS. This allows you to have a maximum of 16 FICON
interface attachments.