Hp Smart Array And Sas/Sata Technology; Sas-2 - HP DL370 - ProLiant - G6 Performance Introduction Manual

Table 2. PCIe device interoperability
PCIe x4 Connector
device type x4 Link
x4 card x4 operation
x8 card Not allowed
x16 card Not allowed

HP Smart Array and SAS/SATA technology

The newest serial, PCIe 2.0 capable Smart Array controllers use Serial Attached SCSI (SAS)
technology, a point-to-point architecture in which each device connects directly to a SAS port rather
than sharing a common bus as with parallel SCSI devices. Point-to-point links increase data
throughput and improve the ability to locate and fix disk failures. More importantly, SAS architecture
solves the parallel SCSI problems of clock skew and signal degradation at higher signaling rates.
The latest Smart Array controllers are compatible with Serial Advanced Technology Attachment
(SATA) technology and include the following features to enhance performance and maintain data
availability and reliability:
• SAS and SATA compatibility — The ability to use either SAS or SATA hard drives lets
administrators deploy drive technology that fits each computing environment. HP Smart Array
controllers can manage both SAS arrays and SATA arrays. Smart Array configuration utilities help
administrators configure arrays correctly so that data remains available and reliable.
• SAS wide port operations — Wide ports contain four single lane (1x) SAS connectors and the
cabling has all four lanes bundled together. SAS wide ports allow balanced SAS traffic distribution
across the links for enhanced performance. In addition, wide ports provide redundancy by
tolerating up to three physical link failures while maintaining the ability to communicate with the
disk drives. The most common use of these wide links is to a JBOD or to an internal server expander
connecting to large numbers of drives. No special configuration is required for this functionality.
• SAS expanders — Low-cost, high-speed switches called expanders can combine multiple single
links to create wide ports and increase available bandwidth. SAS expander devices also offer
higher system performance by expanding the number of hard drives that can be attached to an
HP Smart Array controller. SAS expanders are an aggregation point for large numbers of drives or
servers providing a common connection. By cascading expanders, administrators can chain
multiple storage boxes together. For more information on the HP SAS Expander Card, go to
http://h18004.www1.hp.com/products/servers/proliantstorage/arraycontrollers/sas-
expander/index.html.

SAS-2

SAS-2 and PCIe 2.0 are among the technologies responsible for a significant increase in performance
over past generations of Smart Array controllers. The second-generation SAS (SAS-2) link speed
6.0 Gb/s is double the SAS-1 transfer rate. Operation at SAS-2 link speeds requires SAS-2 compliant
hard drives. SAS-2 eliminates the distinction between fanout and edge expanders by replacing them
with self-configuring expanders. SAS-2 enables zoning for enhanced resource deployment, flexibility,
security, and data traffic management. SAS-2 is also backward compatible with SAS-1.
2 For more information about SAS technology, refer to the HP technology brief titled "Serial Attached SCSI storage technology"
available at http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01613420/c01613420.pdf .
The Serial Attached SCSI - 2 (SAS-2 or SAS 2.0) is a draft standard, and is the product of the Technical Committee 10t
3
Organization. SAS 2.0 is second generation of SAS and is based upon SAS - 1.1. The SAS-2 specification is available from
the 10t website, http://www.t10.org
x8 Connector x8 Connector
x4 Link x8 Link
x4 operation x4 operation
x4 operation x8 operation
Not allowed Not allowed
.
x16 Connector x16 Connector
x8 Link x16 Link
x4 operation x4 operation
x8 operation x8 operation
x8 operation x16 operation
2
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