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The Hard Disk Drive vs. The Solid State Disk
By Joanne De Peralta and Wilson Wei Sheng Wange
Much has been written about solid state disks (SSDs) becoming the next big thing1 in
the IT industry. But as to whether or not we have enough knowledge of how it will
revolutionize the industry is a different question. How much do we really know about SSDs?
If we are to ask people on the streets, it wouldn't come as a surprise that they dont know
much of what an SSD is. Even if they do know, most probably it would be limited to a USB
pen drive, a CompactFlash or a Secure Digital card, which are more on the consumer side of
the storage industry.
Technically speaking, they are not wrong. Most web definitions describe an SSD as a
high-performance plug-and-play storage device that contains no moving parts. Therefore,
given that most of the aforementioned mobile disk storage devices contain no movable
parts, they can certainly be categorized as SSDs.
But then again, there's more to SSDs than being a non-volatile device. The purpose of
this article is to give readers a clearer picture of what an SSD is, its usage as well as
its difference when pitted against the predominant data storage device at present - the
hard disk drive (HDD). More than its non-volatility, this article will reveal how much
potential SSDs have in optimizing the performance of the computing system.
SSD Defined
Here are several ways the SSD is defined:
"A solid state disk (SSD) is electrically, mechanically and software compatible with a
conventional (magnetic) hard disk or winchester. The difference is that the storage medium
is not magnetic (like a hard disk) or optical (like a CD) but solid state semiconductor
such as battery backed RAM, EPROM or other electrically erasable RAM-like chip. This
provides faster access time than a disk, because the data can be randomly accessed and
does not rely on a read/write interface head synchronising with a rotating disk. The SSD
also provides greater physical resilience to physical vibration, shock and extreme
temperature fluctuations. The only downside is a higher cost per megabyte of storage."
"Abbreviated SSD, a solid state disk is a high-performance plug-and-play storage device
that contains no moving parts. SSD components include either DRAM or flash memory boards,
a memory bus board, a CPU, and a battery card. Because they contain their own CPUs to
manage data storage, they are a lot faster (18MBps for SCSI-II and 44 MBps for UltraWide
SCSI interfaces) than conventional rotating hard disks ; therefore, they produce highest
possible I/O rates. SSDs are most effective for server applications and server systems,
where I/O response time is crucial. Data stored on SSDs should include anything that
creates bottlenecks, such as databases, swap files, library and index files, and
authorization and login information."
For the rest of the article, we will compare the HDDs and Flash-based SSDs. The latter
are the most popular type of SSDs employed by the military, aerospace, industrial and
embedded systems industries.
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