Brocade Network Advisor SAN User Manual v11.1x (53-1002167-01, May 2011)

Document Title 643

xx-xxxxxxx-01

Open systems tape pipelining

Open Systems Tape Pipelining (OSTP) can be used to enhance open systems SCSI tape write I/O

performance. To implement OSTP over FCIP, you must enable the following two features:

• FCIP Fastwrite and Tape Acceleration.

• FC Fastwrite.

FCIP Fastwrite and Tape Acceleration

When the FCIP link is the slowest part of the network, consider using FCIP Fastwrite and Tape Read

and Write Pipelining. FCIP Fastwrite and Tape Acceleration are two features that provide

accelerated speeds for read and write I/O over FCIP tunnels in some configurations:

• FCIP Fastwrite accelerates the SCSI write I/Os over FCIP.

• Tape Acceleration 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 Tape Acceleration, you must also

enable FCIP Fastwrite.

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

Fastwrite and Tape Acceleration are enabled by turning them on during the tunnel configuration

process. They are enabled on a per-FCIP tunnel basis.

11 / 001011 3 / 011 Medium QoS

15 / 001111 3 / 011 Medium QoS

19 / 010011 3 / 011 Medium QoS

23 / 010111 3 / 011 Medium QoS

27 / 011011 0 / 000 Class 3 Multicast

31 / 011111 0 / 000 Broadcast/Multicast

35 / 100011 0 / 000 Low Qos

39 / 100111 0 / 000 Low Qos

43 / 101011 4 / 100 High QoS

47 / 101111 4 / 100 High QoS

51 / 110011 4 / 100 High QoS

55 / 110111 4 / 100 High QoS

59 / 111011 4 / 100 High QoS

63 / 111111 0 / 000 -

TABLE 40 Default Mapping of DSCP priorities to L2Cos Priorities (Continued)

DSCP priority/bits L2CoS priority/bits Assigned to: