HP StorageWorks 2/24 FW 07.00.00/HAFM SW 08.06.00 McDATA Products in a SAN Env - Page 203
iSCSI Protocol, TCP/IP network. The target storage device decrypts
View all HP StorageWorks 2/24 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 203 highlights
iSCSI Protocol Implementing SAN Internetworking Solutions 4 iSCSI is based on SCSI protocol that enables hosts to perform block data I/O operations with a variety of target peripherals. Targets include disk drives, tape devices, optical storage devices, printers, and scanners. A standard host-to-peripheral SCSI connection is based on a parallel transport mechanism with inherent distance and device support limitations. For storage applications, these limitations have caused development of high-speed serial transport technologies based on networking architectures such as Fibre Channel and GbE. IP storage networks based on serial gigabit transport layers overcome the distance, performance, scalability, and availability restrictions of parallel SCSI implementations. By using SCSI protocols over network infrastructures, storage networking enables flexible, high-speed block data transfers for applications like tape backup, server clustering, storage consolidation, and disaster recovery. iSCSI protocol defines a means to enable block storage applications over TCP/IP networks. An iSCSI initiator is typically a host (such as a file server) that issues requests to read or write data. The target is a passive resource (such as a disk array) that responds to initiator requests. When a server application sends a request, the operating system generates a packet with SCSI commands and a data request. The packet is encapsulated and encrypted (if required). A packet header is added and the resulting IP packet is transmitted over the TCP/IP network. The target storage device decrypts and disassembles the packet, then separates the SCSI commands and request. SCSI commands are transmitted to the SCSI controller, then to the SCSI storage device. Because iSCSI is bidirectional, the protocol returns data in response to the original request. Compared to the standard SCSI protocol, Fibre Channel provides flexibility in terms of distance extension and switching capabilities. Fibre Channel also preserves the common SCSI controller application programming interface (API). Fibre Channel and iSCSI both preserve the SCSI command set. These common features allow deployment of storage solutions that rely on a combination of parallel SCSI and serial Fibre Channel technologies. Implementing SAN Internetworking Solutions 4-59