HP StorageWorks 2/16V ISS Technology Update Volume 8, Number 5 - Page 6

ISS Technology Update Volume 8, Number 5 HP ProLiant Accelerated iSCSI for Windows User Guide HP Insight software Accelerated iSCSI Pack for Embedded Multifunction server adapters Performance comparison of HP hardware and software accelerated iSCSI - Tolly Group HP iSCSI solutions brief http://bizsupport.austin.hp.com/bc/docs/support/SupportManual/ c00577553/c00577553.pdf http://h18000.www1.hp.com/products/servers/proliantessentials/ aip/index.html http://www.tolly.com/TS/2008/HewlettPackard/iSCSISolutions/To lly208305HPiSCSI.pdf http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA23202ENW.pdf Performance, throughput and compatibility of HP 6-Gb/s SAS drives HP introduced Serial Attached SCSI (SAS) hard disk drives with a 6-Gigabit-per-second (6-Gb/s) interface in the first half of 2009. In conjunction with the newly introduced drive controllers, these drives (Figure 3-1) are the next step in the evolution of the SCSI standard. As this transition begins, it is important to understand the performance, throughput, and compatibility of this new technology in relation to the existing 3-Gb/s SAS drives and controllers. Figure 3-1.HP 6-Gb/s SAS hard disk drive Throughput and performance for 6-Gb/s SAS drives The new 6-Gb/s SAS interface doubles the raw communication bandwidth for each point-to-point link between individual SAS drives and the array controller. As with the previous 3-Gb/s standard, data is sent across the link using 8b/10b encoding for maximum reliability. The link has a maximum theoretical data throughput of 600 MB/s, although its practical maximum is 10% less. This compares to a maximum throughput of 300 MB/s for the older 3-Gb/s SAS interface. In addition to the speed of the interface between the drives and the controller, overall storage subsystem performance is determined by many factors. The most current SAS drives, including those with the new 6-Gb/s interface, have a maximum sustained disk I/O of about 160 MB/s. This is the maximum rate at which data can be continuously read off of the drive, and it is significantly less than the 600-MB/s data bandwidth of a 6-Gb/s SAS interface. It is also less than the 300-MB/s bandwidth 6