A customer is concerned about the long distances between their data centers and significant latencies...

Standard SCSI write operations are inherently sensitive to distance because they require multiple round-trip handshakes before data is actually transmitted. A typical write involves: 1) the Command, 2) a Transfer Ready (XFER_RDY) response from the target, 3) the Data, and 4) the Status. In a long-distance SAN, each of these round trips adds significant "latency wait time," severely degrading performance as distance increases.

To solve this, Brocade (HPE B-series) utilizes a protocol optimization feature known as FastWrite. FastWrite works by creating a Proxy Target (PT) local to the initiator host and a Proxy Initiator (PI) local to the target storage device. When the host issues a SCSI write command, the local Brocade switch (acting as the Proxy Target) immediately sends the XFER_RDY back to the host without waiting for the signal to travel across the long-distance link. This allows the host to send the data segment immediately.

By eliminating the need for every handshake message to traverse the distance multiple times, FastWrite significantly reduces the aggregate latency felt by the application. Architecturally, this enables customers to extend their SAN fabrics over double the distance (and often much further) while maintaining performance comparable to a significantly shorter link. This is critical for asynchronous replication and remote copy applications that issue large I/O blocks. Option C (Write Acceleration) is a generic term often used by other vendors, while FastWrite is the specific, validated Brocade feature name used in HPE Master ASE documentation for this protocol optimization.