Storage No20 8/7/09 10:33 Page 12
12 SSDS
CREATING AN ULTRA-HIGH-
PERFORMANCE TIER OF STORAGE
Adoption for solid state disks (SSDs) within external storage arrays has
become a very hot topic in recent discussions. This is being driven largely
by the fact that advances over the last decade in hard disk drive (HDD)
capacity have outpaced the random IOPS capability of HDDs
Words: By Chris Hoffman, Senior Product Marketing Manager - Embedded Storage Products, Emulex Corporation
The latency inherent to the mechanical nature of HDDs is a major
bottleneck in the movement of data to and from the storage array. High
rotational speed HDDs and striping the data across additional disk drives
“
SSDS REPRESENT A HUGE
OPPORTUNITY TO THE
”
have been common methods used to improve the IOPS capability in storage
systems; however, these approaches do not provide dramatic improvements
EXTERNAL STORAGE MARKET,
in IOPS performance, while resulting in a dramatic increase in power
AS THIS TECHNOLOGY IS
consumption. SSD technology promises to vastly improve IOPS performance
(by a factor of up to 1000), while reducing the total power consumption of a MORE THAN SIMPLY AN
storage array.
EXTENSION OF THE HDD
SSDs’ Entry into the external storage market
TECHNOLOGY ROADMAP
SSDs represent a huge opportunity to the external storage market, as this
technology is more than simply an extension of the HDD technology roadmap.
Rather, SSDs represent a whole new approach to storage technology by
taking advantage of the commoditisation in pricing for NAND Flash different protocols that are possible, but also because of the physical
technology and moving the storage of data off spinning disks and onto Flash. connector differences between the types of SSDs. There are differences in
This move provides storage vendors with a much faster-access alternative to the type of drive connectors and availability for each of the three types of
traditional mechanical HDDs, and helps alleviate the I/O bottleneck issues. SSDs, which can create a bit of a challenge for storage vendors wanting to
However, not all SSDs are created equal. In a fashion that is parallel to deploy SSDs in storage arrays. One way to easily address this challenge is
creating tiered storage with traditional HDDs, SSDs have likewise been through the addition of a drive interposer card. The protocol bridge on the
designed to be used for different applications, ranging from notebook interposer card provides the intelligence to convert the SATA protocol into
applications to mission-critical transactional applications. SSDs can provide FC or SAS, physically and operationally converts the SSDs’ SATA drive
the ultra-high-performance capabilities that are demanded by today’s connector to FC or SAS drive connector and provides dual-ports for path
enterprise storage arrays, but as yet, do not provide high capacity at low failover purposes.
cost per GB. While SATA interface SSDs have recently emerged as lower With the addition of the drive interposer card or integration of the bridge
cost alternatives to their Fibre Channel (FC) interface cousins, the SATA onto the drive itself, a SATA SSD is presented to the storage array’s
interface is not technically acceptable for use in the back-end of external controller as if it were an ultra-high-performance FC and SAS SSD.
storage systems, necessitating that all SATA SSDs be bridged to either the Furthermore, SATA SSDs from multiple vendors can be mixed and matched
FC or Serial Attached SCSI (SAS) protocol. in the same storage array, because the protocol bridge provides an
abstraction layer that can be customised to make any drive look and act the
Creating an ultra-high-performance tier of storage same to the storage array controller, regardless of who manufactured it.
While the primary drivers for incorporating SSDs into external storage are to While SSDs represent a whole new era for storage arrays, it is not
navigate around the I/O bottlenecks and to save power, the variety of back- necessary to reinvent the wheel when creating a cost-effective and ultra-
end storage protocol support needed (both FC and SAS) and the difficulty of high-performance storage tier. As companies struggle with balancing the
meeting mission-critical storage requirements have proven to be very demands for increased performance with increased capacity, the answer is
challenging for potential suppliers. One way of simplifying this complexity is to use SATA SSDs with an enterprise-ready protocol bridge to create an
to take advantage of the robust capabilities of an enterprise-class protocol ultra-high-performance storage tier. Through the simple addition of a drive
bridge by incorporating it along with the SATA SSD devices. This can be interposer card or integrating the protocol bridge into the SSD device,
done with an external bridge interposer card, or by integrating the bridge storage vendors are now able to mix and match ultra-high-performance SSDs
directly into the SATA SSD. with high-capacity HDDs, greatly extending the value and functionality of their
However, there are challenges in doing this, not only because of the storage arrays.
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