ENTERPRISE
SSDs
storage devices in enterprise computing systems. Using
flash storage in media players is fundamentally different
from deploying the technology in 24/7 mission-critical
operations.
With the advent of this new category of solid-state
device, the potential for using SSDs in enterprise systems
has become a reality, with profound implications for system performance. At the same time, leveraging the power
of SSDs is difficult, and even identifying true enterprise-class SSDs is a major challenge. With these challenges in
mind, we develop in this article a framework that can be
used to assess SSD technology and determine its enter-prise-readiness.
ARCHI TEC TING A PERFORMANCE SSD
The very first enterprise-class SSD was introduced in 2007.
One of the key architectural dimensions of the product
was that it combined the best attributes of two memory
technologies: flash and DRAM. That dimension coupled
with complex controller technology results in an entirely
new class of SSDs for markets where performance is the
key reason why customers would use SSDs instead of
HDDs.
The primary applications that are now benefiting
from this technology are those that are heavily dependent upon the drive I/O performance—for example, in
enterprise storage and server applications where the I/O
performance of the drives has a direct impact on the overall system performance and where cost is measured in
performance and not just in capacity (cost/performance).
In such applications, increased I/O is equal to increased
revenue for the end user.
Two examples of such applications are:
• Those that require a large number of the fastest HDDs
( 15,000-RPM FC/SAS drives). To achieve fast I/O per-
formance, these systems artificially limit the amount of
accessible drive space to only the outside orbit of the
platters. This limits mechanical spindle movements. In
addition, the data is striped across many drives to get
to the desired IOPS (I/O operations per second) at the
system level. One example of such an application has
had as many as 9,000 drives in one system to achieve the
required I/O performance. In this application an enterprise-class SSD has been able to replace the mechanical
drives at the rate of 30 to one, reducing not only the
number of drives from 9,000 to 300, but also the number
of racks, enclosures, controllers, cables, switches, power
supplies, and all other associated electronics. Switching to
SSDs delivered not only a 50-percent upfront cost savings,
but also a 90-percent cost savings associated with power
and maintenance of the system over multiyear operations. Figure 1 illustrates the random I/O performance of
an enterprise SSD that makes these cost savings possible.
• Enterprise server applications where the overall performance of the system is limited by I/O performance of the
drive subsystem. In these applications, there is another
category of enterprise SSD that offers much lower cost
(relative to the highest-performance SSD) yet maintains
overall performance characteristics of 10 times today’s
mechanical hard drives. With this approach, the additional cost associated with SSDs is justified by the overall
performance-improvement gains at the server level and
the power savings.
FIGURE
1
Performance Comparison:
Enterprise SSD vs. Enterprise HDD
STEC Enterprise SSD
45,000 IOPS
Enterprise HDD
350 IOPS
