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Samsung Electronics' recently announced that its three Solid State Disk (SSD)
drives have been officially recognized by Microsoft Corporation as fully
qualified Windows-compatible peripherals. This news has again set off an old
debate of whether SSD can be an effective alternative to hard disk drive?
SSD is seen as a data storage device that uses non-volatile memory such as
flash, or volatile memory such as SDRAM, to store data, instead of the spinning
platters found in conventional HDDs. While not technically 'disks' in any sense,
these devices are so named because they are typically used as replacements for
disk drives in situations where conventional drives are impractical.
Apart from the DRAM or flash memory boards, an SSD comprises of memory bus
board, a CPU and a battery card. Since the SSD has its own CPU to manage data
storage, they are a lot faster than conventional rotating hard disks. The
typical access time for a flash-based SSD is about 35 to 100 microseconds,
whereas a rotating disk's is around 5,000 to 10,000 microseconds. That makes a
flash-based SSD approximately 100 times faster than a rotating disk. In short,
these are high-performance plug-and-play storage devices that contain no moving
parts. But the good old debate on SSD has been whether it justifies as a
replacement to HDD?
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| NEW THREATS TO SSD Even before SSDs
become popular there are newer technologies that are possible threats to
SSDs. The two main technologies used in SSDs today-flash and battery-backed
RAM- have been around for over a decade and hold the promise of decreasing
cost and increasing capacity in line with Moore's Law. But in a five-year
time frame, there are three other technologies, which may become
commercially viable in the SSD market space.
- Ferroelectric Random Access Memory (FRAM): Invented by
Ramtron, FRAM was first shipped in 1992 and with over
100 million devices this is an established non-volatile memory technology
which has much faster write speeds than flash and much greater endurance
(typically 10 billion write cycles, compared to 1 million writes for
flash). However, current FRAM products offer approximately 1,000 times
less capacity than either DRAM or flash.
- LCD storage technology: A company called Dataslide has
been working on this technology, which it claims will offer faster access
times than current hard drives. In a paper distributed in Q4 2004 the
company claimed to have working prototypes, which offer the equivalent of
72,000 RPM performance (four times faster than the fastest hard drives
today) and says that their technology is scalable to 12 million RPM using
current materials. If true, that would impact SSDs in non-ruggedized
server applications. But the company has yet to ship any commercial
products.
- Magneto resistive RAM: Patented by NVE, this technology
has been licensed to several semiconductor companies. Freescale, a
Motorola spin-off, started sampling a 4M-bit device in Q3 2004. Cypress
Semiconductor offers a 256k-bit device.
SOURCE: StorageSearch.com |
Early adopters
SSD has been around for quite some time now. In the late 1970s manufacturers of
industrial control systems used SSDs to hold programs, because the hard disks
available at that time were expensive and unable to operate reliably in a
factory environment. For the same reasons, SSDs were used in military embedded
systems.
Meanwhile, durability of HDDs improved during the 1990s and it became the
most used storage device. But HDDs still remained sensitive to extreme
temperatures. By the end of the 1990s flash solid-state disks again started
replacing HDDs in most military applications due to superior operating
temperature, lower weight, lower power and faster performance. Unlike the HDD,
SSD can withstand extreme shock and vibration with data integrity and without
any danger of data loss.
SSD's ability to perform in extreme conditions makes it an important device
in military operations. Only SSD can withstand the military standards of
operating under temperatures ranging from -60°C to +95°C. Be it in defense,
aerospace or aviation applications, SSDs are being used as a reliable data
storage medium under extreme conditions. Boeing and Airbus uses SSDs as the data
recorders in their planes.
High-cost hurdle
If such is the superiority of SSD as a storage medium, what is keeping this
technology away from the masses? Cost obviously is one of the reasons for the
slow pace of SSD's popularity. In fact, the only reason why notebooks PCs don't
have SSDs inside instead of a HDD is because most people can't afford the SSD
technology. Per GB cost of SSD available today are too expensive compared to the
conventional disk.
But propagators of SSDs believe the cost is justified when offset with the
brilliant positives it has over the fastest HDD. According to technical experts,
hard disk drive is the only component that has not kept pace with the speeds of
CPUs and memory, which prominently decided the performance of a computer. And
due to this limitation of slow-spinning hard disk drive, the CPU fails to
deliver its full potential in running a computer at the maximum best.
It is true that CPU performance has lived up to meet the Moore's Law. But
the limitation of HDDs has restrained the processor from running at its best.
According to analysts, by adding high speed SSDs for storage needs, applications
can speed up from two to 40 times. It can deliver more than 1,000 times the
random access speed of hard disk based systems.
In a way, if deployed correctly this works out a lot better than adding more
processors, memory and software licenses to make the systems run faster. The
high cost of SSD may not compare with the low-cost HDDs, but it any day works
out cheaper than a CPU upgrade, at the same time delivering same speed benefits.
Faster applications
SSDs today have mostly been limited to industrial and military applications.
However, manufacturers are now positioning SSDs as an effective component for
server applications and server systems, where I/O response time is crucial. If
the use of a SSD is speeding up an enterprise server with thousands of networked
users then it's a mistake to think of the SSD as replacing storage. In fact it
is replacing servers and software licenses.
Enterprises are also responding well by implementing SSDs in their tiered
storage and to optimize their storage architectures. SSDs have been an
excellent choice in industrial PCs. It's all about how much safer data is stored
in solid-state drives rather than a fragile mechanical-based device.
Use in portables
Notebooks represent the fastest growing segment of the worldwide PC market. The
biggest challenge for notebook manufacturers is to make notebooks smaller,
lighter, faster and having longer battery life. HDDs consume lot of battery
power in a notebook. Substituting HDDs with flash memory-based SSDs will make
notebooks smaller, faster and less power consuming than HDDs. Most computer
makers have plans to substitute HDD with SSD.
The latest news is from Samsung, which has released the world's first
notebook embedded with a 32GB flash-based SSD. Called the Samsung Q30, this
12.1-inch screen notebook marks the entry of NAND flash into a commercial mobile
computing application. The notebook is priced at $3,700-and is available in the
Korean market.
The SSD enabled notebook resolves many of the traditional challenges of
mobile computers. The company claims that data in flash memory are much more
secure against external shocks that can occur when transporting a mobile
computer. The SSD can withstand about twice the impact that would cripple a
regular HDD. In addition, stored data can be more easily retrieved from flash
memory than traditional hard drives when PCs are dropped or liquid is spilled on
the device. These mobile computing devices are the ideal solution for
professionals and executives who are constantly on the move.
According to Samsung statement the SSDs used in its mobile devices reads 300
percent faster (53MB/s) and writes
150 percent quicker (28MB/s) than normal hard drives. As a result, multiple
application programs can operate simultaneously and large volumes of data can be
edited and reproduced more efficiently.
The Microsoft Windows
XP operating system boots up 25-50 percent faster on the SSD than on other
drives. The typical notebook PC will generate around 30DB of operating noise,
while the Samsung Q30-SSD operates in complete silence.
Heat and power
Along with the lower power consumption, there is also much lesser heat
dissipation for systems using flash-based SSDs as their data storage solution.
This is due to the absence of heat generated from the rotating/movable media.
This certainly proves to be the one of the main advantages of flash-based SSDs
relative to that of a traditional HDD. With less heat dissipation, it serves as
the ideal data storage solution for mobile systems such as PDAs, notebooks, etc.
Users can do away with large cooling fans, internal power supply and batteries
for large storage arrays in storage area networks.
In addition to speed, reliability and mortality rate are being positively
affected by the SSD's non-volatility; they also consume less power than
traditional HDDs. No additional power is required to activate the platters or
the mechanical arms present in most HDDs. Its power consumption is practically
only a fraction of a HDD.
Reliability factor
The most debated topic in the favor of the SSD has been its reliability. HDD
lovers are very skeptical about the reliability of data stored in SSDs.
According to them flash-based SSD wears out its usable capacity and is not good
for applications requiring high read/write cycles.
For example a commercial server applications may have an unusually high ratio
of write to read cycles such as algorithm development, signal processing
research and pure mathematical research. Burning out even a bit can give wrong
results. Whereas, HDDs are optimized for operating systems, file systems, and
many applications.
Here is what SSD lovers have to say: Hard disk failure is a common occurrence
in this age of desktops and notebooks simply because of the wear and tear of the
mechanical components inside a HDD. A flash-based SSD is different. Although the
most common flash chips have around 3,00,000 write cycles, the best flash chips
are rated at 1,000,000 write cycles per block. On top of that, flash SSD
manufacturers employ different techniques such as 'balancing algorithm'or 'wear
leveling' to increase the longevity of the drives.
“Where do you think the most important data in your computer is stored?” asks
a SSD propagator answering, “It is the BIOS-a relative of flash memory not a
relative of HDD.” Also the fact that military has long been using SSDs for its
applications requiring storage, talk about its reliability.
To complete the list Microsoft has validated that Samsung SSDs to meet all of
the requirements for storage media in a Windows operating environment.
-NELSON JOHNY Page(s) 1
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