Specifications

The ESS supports increased connectivity with the use of fibre-channel (SCSI-FCP
and FICON) directors. Specific details on status, availability, and configuration
options for the fibre-channel directors supported by the ESS are available on the
Web at:
www.storage.ibm.com/hardsoft/products/ess/supserver.htm
The ESS supports the switched-fabric topology with point-to-point protocol. You
should configure the ESS fibre-channel adapter to operate in point-to-point mode
when you connect it to a fabric topology. See Figure 6.
Arbitrated loop
Fibre-channel arbitrated loop (FC-AL) is a ring topology that enables you to
interconnect a set of nodes. The maximum number of ports that you can have on a
fibre-channel arbitrated loop is 127. See Figure 7 on page 15.
The ESS supports FC-AL as a private loop. It does not support the fabric-switching
functions in FC-AL.
The ESS supports up to 127 hosts or devices on a loop. 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.
Note: The ESS does not support FC-AL topology on adapters that are configured
for FICON protocol.
S008945N
1
2
2
1
3
3
3
Legend
1 is the host system.
2 is the ESS.
3 is a switch.
Figure 6. Switched-fabric topology
14 ESS Host Systems Attachment Guide