Written by Lyth0s
Thursday, 17 March 2011 21:35
Solid State Drives vs. Hard Disk Drives (SSD vs HDD)
Solid state drives (SSD) are data storage devices that used to store persistent data. In terms of function SSD's serve the same purpose
as your typical hard disk drive (HDD), but are much faster than your typical hard drive. The main difference between solid state drives
and hard disk drives is that hard disk drives are electromechanical, meaning that they have moving parts. In a HDD the hard drive has an
actual magnetic disk that needs to spin and it has a moving read/write head. So hard disk drives are slower because they need to wait
for these moving parts to get into place before they can save information to the hard drive or before then can read files. In contrast,
solid state drives have no moving parts and they store information in microchips, much like a USB flash drive (but much faster!) and they
can instantly start saving information or reading files, without having to wait for any moving parts to get in place.
Solid State Drive (SSD) Pro's and Benefits
Solid state drives have no spin up time, meaning they are instantly ready to read or write to the drive, while HDD's may need up to around
2 seconds before they can actually access the drive. Solid state drives are also able to both read and write files at about twice the speeds
of hard disk drives. This means your computer will boot faster and video games and other programs will load quicker!
SSD's also do not need to be defragmented, in contrast a fragmented HDD will greatly
reduce read/write times of the hard disk drives and slow your computer down. SSD's are also much less likely to break if you drop them or if they sustain an impact,
because they have no moving parts. Strong magnetic fields can corrupt an HDD, while the SSD's are unaffected by magnets. Solid state drives also consume much less power and produce much less heat than hard disk drives do (2W SDD vs 7W HDD power consumption).
Solid State Drive (SSD) Cons
The only two current cons to having a solid state drive is if you need to encrypt data or you don't want to fork out the extra cash to buy one. Currently the most popular SSD are
based on MLC NAND flash memory and this type of memory cannot overwrite files and can only write information to empty blocks
or previously erased blocks. This means that if you have a file on your computer and you use a program to encrypt it, the old
data is not overwritten and can still be accessed. Thus you would need to encrypt the file, and then securely erase the old
data, preferably with a secure erase feature built into the SSD. If you need to encrypt data I highly recommend buying a SSD that has a
"Secure Erase" feature built into the drive or look into Truecrypt creating an entire encrypted partition of the drive and Windows
installation. Solid state drives are currently much more expensive than HDD's. Currently a SSD costs about $1.80 USD per gigabyte, while a HDD costs about $0.11 USD per
gigabyte (As of 3/17/2011).
Solid State Drive (SSD) Lifespan
SSD also has a limited life span due to the limited number of write cycles. However, today's current MLC SSD's have an Mean time between failures (MTBF) of 2,000,000 hours,
which simply put means that your SSD will typically last for 228 years! They technically have a limited amount of writes they can perform too, but they are able to sustain about
40 years of constant, non-stop, writing before they would start failing. Hopefully that puts the myth that SSD's will not last very long to rest, unless you need to have your
SSD last you for over 228 years...
The table below gives a pretty good compare and contrast between HDD vs SSD.
HDD vs SSD
Hard Disk Drive (HDD)
Solid State Drive (SSD)
|Sensitive to Magnets
||Magnets will alter or destroy data
||Magnets have no effect on data
||7 Watt average
||2 Watt average
|Time to Spin Up
||Up to 2 seconds before HDD can read/write to drive
||Instantaneous, able to read/write immediately
|Read Speed (SATA)
||Roughly 100MB/s, can very depending on level of fragmentation
|Write Speed (SATA)
||50-70 MB/s, can very depending on level of fragmentation. Up to 118 MB/s on HDD's such as the WD Velociraptor.
||May fail due to vibrations or impact, usual MTBF of 1,500,000 hours (171 years)
No finite number of writes
|MTBF of 2,000,000 hours, AKA 228 years.
Or about 40 years of non-stop writing due to write cycle limits
||HDD's can overwrite encrypted data right on top of the old data
||SSD's need a secure erase feature or total partition encryption. (Can not overwrite data, data must be erased first)
||HDD's cost about $0.11 USD per gigabyte as of 3/17/2011
||Solid state drives cost about $1.80 USD per gigabyte as of 3/17/2011
||HDD's typically make noticable sound during read/write and spin up times.
||Solid state drives have no moving parts and make no sound.
||Very little heat produced, but still 3 times more heat than SSD's.
||Only produce about 1/3 the amount of heat of an HDD.
|Sensitivity to Shock
||Very sensitive, hard disk drive heads and disks may break due to shock or vibration
||Solid state drives have no moving parts and are very resistant to shock and vibration
||Level of fragmentation of an HDD will significantly reduce read/write speeds
||No need to defragment solid state drives due to not having any read/write heads to find the data
Western Digital Caviar Blue 500 GB SATA III
Intel 320 Series 120 GB SATA 3.0 Gb-s 2.5-Inch Solid-State Drive (SSD)
Last Updated on Wednesday, 07 December 2011 15:43
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