SSD vs HDD

Up until this year, PC buyers had very little choice for what kind of primary storage they got with their laptop, nettop, notebook, or desktop. With the price of SSD (Solid State Drive) storage coming down, they are now a regular feature on many machines. But which is best to get, an SSD or HDD (Hard Disk Drive)?

What is an SSD?

SSD stands for Solid State Drive. You’re probably familiar with USB memory sticks, SSD can be thought of as an oversized and more sophisticated version of the USB memory stick.  Like USB, there are no moving parts to an SSD, information is stored in microchips.  For comparison, a hard drive uses a mechanical arm with a head which moves around the storage platter.  This difference is what makes SSD so much faster.  As an analogy, what’s quicker, having to walk across the room to retrieve a book to get information or simply magically having that book open in front of you when you need it?  SSD’s simply don’t need to move around to get the information they need.

A typical SSD uses what is called NAND-based flash memory, this is a non-volatile type of memory, which permits you to turn off the disk without losing what is stored on it. During the early days of SSD, rumours floated around saying stored data would wear off and be lost after a few years, finally, after some advanced tests, results shows that you can read and write to an SSD all day long and the data storage integrity will be maintained, and the data storage life of an SSD can outlive you. With the typical life span of a computer being 3-7 years depending on usage, then this is more than enough for anyone.

An SSD does not have a mechanical arm to read and write data, it instead relies on an embedded processor (or “brain”) called a controller to perform a bunch of operations related to reading and writing data.  The controller is a very important factor in determining the speed of the SSD, decisions it makes related to how to store, retrieve, cache and clean up data can determine the overall speed of the drive.

Finally, you may be wondering what an SSD looks like and how easy it is to replace a hard drive with an after market upgrade to an SSD.  If you look at the images below you’ll see the top and underside of a typical sized 2.5” SSD, the technology is encased inside either a plastic or metal case that is exactly the same dimensions as a typical HDD. They even have the same SATA connection. So, if you have a HDD, the chances are you will be able to have an SSD also. The form factor of the SSD is actually the same as a regular hard drive, it comes in a standard 1.8”, 2.5” or 3.5”.

What is a HDD?

Hard Disk Drives, or HDD are the most represented form of storage devices for computers. A HDD uses magnetism to store data on a rotating platter.  A read/write head floats above the spinning platter reading and writing data.  The faster the platter spins, the faster an HDD can perform, typical laptop drives today spin at either 5400 RPM (Revolutions Per Minute) or 7200RPM, some server based platters can spin at up to 15,000 RPM.

HDD’s predominantly use the SATA interface.  The most common size for laptop hard drives is the 2.5” form factor while a larger 3.5” form factor is used in desktop computers.  The larger size allows for more platters inside and thus more storage capacity. Below is an example of what a HDD looks like using the Seagate Barracuda 3TB hard drive, this example is a 3.5″ desktop HDD:

SSD/HDD Direct Comparison Table

Attribute	SSD (Solid State Drive)	HDD (Hard Disk Drive)
Power Draw / Battery Life	Less power draw, averages 2 – 3 watts, resulting in 30+ minute battery boost	More power draw, averages 6 – 7 watts and therefore uses more battery
Cost	Expensive, in excess of $1.50 per gigabyte	Only around $0.10 per gigabyte, very cheap
Capacity	Typically not larger than 512GB for notebook size drives	Typically 500GB – 2TB for notebook size drives
Bootup Time for Windows 7	Around 22 seconds average bootup time	Around 40 seconds average bootup time
Noise	There are no moving parts and as such no sound	Audible clicks and spinning can be heard
Vibration	No vibration as there are no moving parts	The spinning of the platters can sometimes result in vibration
Heat Produced	Lower power draw and no moving parts so little heat is produced	HDD doesn’t produce much heat, but it will have a measurable amount more heat than an SSD due to moving parts and higher power draw
Failure Rate	Mean time between failure rate of 2.0 million hours	Mean time between failure rate of 1.5 million hours
File Copy / Write Speed	Generally above 200 MB/s and up to 500 MB/s for cutting edge drives	The range can be anywhere from 50 – 120MB / s
Encryption	Full Disk Encryption (FDE) Supported on some models	Full Disk Encryption (FDE) Supported on some models
File Opening Speed	Up to 30% faster than HDD	Slower than SSD
Magnetism Affected?	An SSD is safe from any effects of magnetism	Magnets can erase data

Conclusion

The major advantage of an HDD is that it is capable of storing lots of data cheaply.  These days 1 TeraByte (1,024 gigabytes) of storage is not unusual for a laptop hard drive, and the density continues to grow.  Cost per gigabyte is only around $0.10 these days for a HDD, that’s amazing when you compare it to the near $1.75 /GB cost for an SSD.  If you want cheap storage and lots of it, using a standard hard drive is definitely the more appealing way to go. But if you prefer the technology, the performance, and the speed turn to SSD.

A lot of users, including Kev Quirk, the creator of RefuGeeks use a combination of both SSD and HDD to give them best of both worlds. What he has on his desktop is a small, 16GB SSD which has his operating system (Ubuntu 12.04) and also a 320GB traditional HDD which has all of his data stored. This means that he has the high performance of an SSD, yet the high storage capacity of the HDD.

Still, the cost for SSD’s is coming down rapidly. A 120GB SSD will cost around $150, so this isn’t a huge amount to pay out for such a big performance increase.

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