Fabric OS FCIP Administrators Guide v6.4.0 (53-1001766-01, November 2010)

52 Fabric OS FCIP Administrator’s Guide

53-1001766-01

Options for enhancing tape I/O performance

There are two options available for enhancing open systems SCSI tape write I/O performance:

• FCIP Fastwrite and Open Systems Tape Pipelining (OSTP)

• FC Fastwrite

FCIP Fastwrite and OSTP are implemented together. FC Fastwrite is an FC-FC routing alternative

that disables the local Ethernet ports (ge0 and ge1), making it impossible to configure FCIP

Fastwrite and OSTP and FC Fastwrite on the same 7500 or FC4-18i blade. Refer to Appendix A,

“Fibre Channel Fast Write (FCFW)” for information about FC Fastwrite.

FC Fastwrite flows may be routed to another 7500 or FC4-18i blade on the FC network. This 7500

or FC4-18i blade may have active FCIP tunnels over an IP network. FC Fastwrite flows may be

passed through the FCIP tunnel, but only if the FCIP Fastwrite option is disabled on the tunnel.

FCIP Fastwrite and OSTP

When the FCIP link is the slowest part of the network, consider using FCIP Fastwrite and OSTP. FCIP

Fastwrite and OSTP are two features that provide accelerated speeds for read and write I/O over

FCIP tunnels in some configurations:

OSTP accelerates SCSI read and write I/Os to sequential devices (such as tape drives) over FCIP,

which reduces the number of round-trip times needed to complete the I/O over the IP network and

speeds up the process. To use OSTP, you must also enable FCIP Fastwrite.

Both sides of an FCIP tunnel must have matching configurations for these features to work. FCIP

Fastwrite and OSTP are enabled by turning them on during the tunnel configuration process. They

are enabled on a per-FCIP tunnel basis. See “Creating an FCIP tunnel” on page 61 for details.

Consider the constraints described in Table 12 when configuring tunnels to use either of these

features.

TABLE 12 Using FCIP Fastwrite and OSTP

FCIP Fastwrite OSTP

Each GbE port supports up to 2048 simultaneous

accelerated exchanges, which means a total of 2048

simultaneous exchanges combined for Fastwrite and

OSTP.

Each GbE port supports up to 2048 simultaneous

accelerated exchanges, which means a total of 2048

simultaneous exchanges combined for Fastwrite and

OSTP.

Does not affect FICON traffic Does not affect FICON traffic

FCIP Fastwrite and FC Fastwrite are mutually exclusive. OSTP uses FCIP Fastwrite, not FC Fastwrite.

Does not support multiple equal-cost path

configurations (see “FCIP Fastwrite and OSTP

configurations”).

Does not support multiple equal-cost path

configurations or multiple non-equal-cost path

configurations (see “FCIP Fastwrite and OSTP

configurations”).