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HOME REVIEWS CONTACT ABOUT March 14, 2009
Are Solid-State Memory Drives (SSD)
in Your Future?
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In
today’s computer dependent world, we are always on the lookout for the next
"new thing". Often times, the thing has been a new microprocessor from
Intel or AMD. However, in recent years,
the microprocessor is often not the limiting factor with computer performance.
While
hard-drive memory capacities have increased significantly in recent years, the
access speed has remained relatively constant.
It's an issue/problem fundamental to the technology. The hard-drive is mechanical, and efforts to
improve speed have been receiving diminishing returns.
A
technology that is competing with the conventional hard-drive (HDD) is the
solid-state drive (SSD). An SSD is not
mechanical; it is based on "flash memory", the same computer chip
technology used to store pictures with your digital camera. An SSD drive was a novelty only 3 years ago,
but no longer.
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An SSD can outperform conventional mechanical hard
drives because it is 4X smaller and lighter, is up to 50X faster, is more
reliable because there are no moving parts, produces less heat, and uses less
power. SSD drive memory capacity has
improved and 250 gigabyte SSD drives are now available. Currently, the main drawback is price.
SSD
Drives are still more expensive than conventional HDD. An
Flash
memory is capable of a finite number of rewrites to each memory cell (so are
conventional hard-drives). Significant
improvements to the technology have been made in recent years. To further minimize this issue, Intel
developed "load leveling".
This technique ensures that all of the memory cells on the SSD receive a
similar workload. Most SSD manufacturers
now utilize comparable techniques. An
SSD should last 10 years or more for the average user.
The
primary reason for the rosy future of SSD is access speed. A fast conventional HDD has access times
equal to about 5 milliseconds. It sounds
fast, but when the microprocessor is capable of millions of instructions per
second (MIPS), 5 milliseconds is a bottleneck.
SSD can have 100 microsecond access times (50X faster).
An
important issue when trying to utilize this SSD speed capability is the
potential bottleneck caused by the interface.
There are 3 common interfaces used today with SSD drives.
The SATA
interface is currently the most common interface used for conventional HDD, but
a SATA interface has been limited in total throughput, both send and receive,
to about 3 Gbps. This can be too slow
for SSD, causing performance disruptions.
Some SSD drives are capable of over 5 Gbps throughput.
SAS
(Serial Attached SCSI) is another alternative.
SAS is a point-to-point technology with at least four channels. Each channel is capable of throughput of 3
Gbps in each direction (a total of 6 Gbps per channel).
A
third alternative is to implement the SSD with a PCI Express interface. A PCI Express interface has unidirectional
data paths, one send and one receive, each at 2.5 Gbps for a throughput of 5
Gbps.
Seagate
Technology, in conjunction with AMD, recently announced the Serial ATA 6-Gbps
storage interface, also called SATA Revision 3.0, a next-generation technology
that is capable of twice the speed of the fastest SATA interface available
today. This technology was demonstrated
for conventional hard drives, but has obvious application to the SSD market.
It
is possible to maximize the performance advantage of the SSD technology with
careful selection of the appropriate interface.
Sun Microsystems Endorses SSD
Sun
Microsystems, a leading maker of engineering workstations (very high
performance computers), is predictably committing strongly to SSD
technology. Sun can be seen as a
bellwether for the PC industry. If Sun
endorses the technology at the current price, as the prices reduce, the
technology would logically be utilized by the mainstream PC user. This pattern has been seen for other new
technologies, such as advanced DDR RAM memory.
Sun
has said it is adding SSD technology to its systems to increase their
performance for I/O intensive applications. Late last year, Sun introduced SSD
in its
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"SSD technology helps customers achieve up to 65
times faster response times, up to eight times better throughput and up to 38
percent less power consumption than servers with traditional spinning hard disk
drives.” Raymond Austin, Sun Microsystems
An
SSD drive will be more tolerant for harsh operating environments and will be
more reliable. Computers utilizing SSD
drives will experience faster application load times and better overall
performance. An SSD drive can emulate a traditional mechanical hard disk drive
(HDD). This makes replacing the traditional HDD for an SSD in your current
system less complicated. For most
people, an SSD is the most logical upgrade to their system.