A storage processor is interposed between initiators and storage targets, such as storage appliances or storage devices in a storage network. The storage processor presents a target interface to the initiators and an initiator interface to the targets, and the storage processor transparently intercepts and processes commands, data and/or status information (such as iSCSI R2T and data PDUs) sent between the initiators and the targets. The storage processor presents a virtual device to the initiators and transparently implements the virtual device on the targets, such as a RAID-1. The storage processor negotiates acceptable operational parameters, such as maximum segment size, with the initiators and targets, such that the storage processor can pass data received from the initiators to the targets, without excessive data buffering. Consequently, when an initiator issues a write command, the storage processor is able to forward each segment of data received from the initiator to the appropriate target(s), without first buffering all segments of the write command.