Thursday, December 15, 2011

Hard Disk Drive (HDD) vs Solid State Drive (SSD)

Maybe you're asking, what the heck is an SSD?

Solid state drives (SSD) are data storage devices that used to store persistent data. In terms of function, SSD serves 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 an 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.

This table below gives comparison between HDD and SSD


Hard Disk Drive (HDD)

Solid State Drive (SSD)

Sensitive to Magnets
Magnets will alter or destroy data Magnets have no effect on data

Power Consumption
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 250 MB/s

Write Speed (SATA)
50-70 MB/s, can very depending on level of fragmentation. 200-250MB/s.

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

So, in overall, SSD is pretty much better than HDD, but far more expensive (you can get a 500GB HDD with about $55, while you need almost $900 for an SSD with the same capacity).. Perhaps you're asking, "Does buying an SSD really worth it?" Well, if you're looking for a more powerful and stronger storage device, SSD is the answer..

1 comment:

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