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SCSI host adapters
The ESS provides an ultra-SCSI interface with SCSI-3 protocol for attachment to
host systems with UNIX, Windows NT, Windows 2000, and the OS/400 operating
systems. The interface also supports SCSI-2 protocol.
The ESS supports up to 32 ports; two per SCSI host adapter. Each port supports
an ultra-SCSI or SCSI-2 fast and wide differential-connection to the host system. A
SCSI-2 fast and wide differential connection is a subset of ultra-SCSI.
3002
Order host cables separately (see "Connection hardware" on page 37).
Fibre-channel host adapters
The ESS supports the point-to-point topology, the switched fabric topology and the
fibre channel arbitrated loop topology, private loop profile. When using the loop
topology, the ESS has no restrictions on the number of hosts or devices that you
can attach on a loop, other than the architectural limit of 127. However, the loop
goes through a loop initialization process (LIP) whenever you add or remove a host
or device from the loop. LIP disrupts any I/O operations currently in progress. For
this reason, IBM recommends that you only have a single host and a single ESS on
any loop (point-to-point loop).
To have IBM install short-wave fibre-channel adapters on your ESS, order FC 3022
(IBM P/N 54G3384). This feature code includes a 31 m (93 ft), 50 µM short-wave
optics cable. These fibre-channel adapters incorporate short-wave laser
transmitters. You can order and have IBM install a maximum of 16 fibre-channel
adapters on the ESS. Each adapter has a single host port. See your IBM field office
about longer cables or 62.5 µM cable.
3022
ESCON host-adapters
Each ESCON host adapter provides two ESCON channel interfaces for attachment
to up to 32 channels. Each ESCON channel supports 64 logical paths, for a total of
2048 paths.
3011
Order host cables separately (see "Connection hardware" on page 37).
Device adapters
The standard configuration for the ESS includes eight device (DDM) adapters.
Each device adapter provides two device loops (4 interfaces) that operate at up to
160 MB per second, depending on the DDM type that you attach. Each loop
supports up to 48 DDMs.
Because the device loops are between adapter pairs, both clusters 1 and 2 can
access all DDMs on a loop. See "Failover protection" on page 15 for the
advantages to this configuration.
30
ESS Introduction and Planning
SCSI host adapter (optional 1 - 16)
Fibre-Channel Short Wave host adapter (optional 2-16)
Complimentary 31m, 50 micron host cable included.
ESCON host adapter (optional 2, 4, 6, 8, 10, 12, 14, and 16)
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