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ISS Technology Update
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
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
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/4AA2-
3202ENW.pdf
Volume 8, Number 5
6
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