What is an HDD?
Hard Disk Drives, or HDDs were first introduced by IBM in 1956, nearly 60-year old technology. An 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.
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 / GB these days for an 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.
HDDs 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. Some desktop hard drives can store up to 4TB of data. HDDs look essentially the same from the outside as an SSD.
What is a 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 humble USB memory stick. Like a memory stick, there are no moving parts to an SSD. Information is stored in microchips. Meanwhile, a hard drive uses a mechanical arm with a read/write head to move around and read information from the right location on a 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? That’s how an HDD compares to an SSD, it simply requires more physical labor (mechanical movement) to get information.
A typical SSD uses what is called NAND-based flash memory, this is a non-volatile type of memory. What does non-volatile mean you ask? The simple answer is that you can turn off the disk and it won’t “forget” what was stored on it. This is of course an essential characteristic of any type of permanent memory. During the early days of SSD rumors floated around saying stored data would wear off and be lost after only a few years. Today this is not true, you can read and write to an SSD all day long and the data storage integrity will be maintained for well over 200 years. In other words, the data storage life of an SSD can outlive you!
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. We won’t get into the nitty gritty of the details for the various tasks it performs such as error correction, read and write caching, encryption and garbage collection to name a few but suffice to say, good controller technology is often what separates an excellent from simply good SSD. An example of a fast controller today is the SandForce SATA 3.0 (6 Gb/s) SSD controller that supports up to 500 MB per second read and write speeds.
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” size that can fit into the housing and connectors for the same sized hard drives. The connector used for these standard sizes is SATA, there are smaller SSDs available that use what’s called mini-SATA (mSATA) and fit into the mini-PCI Express slot of a laptop.
These days most people are buying laptops for their computing needs and you have to make the decision between getting either a Solid State Drive (SSD) or Hard Disk Drive (HDD) as the storage component. So which is best to get, a SSD or HDD?
SSD
Battery Life : Less power draw, averages 2 – 3 watts, resulting in 30+ minute battery boost
Cost : Expensive, in excess of $1.50 per gigabyte
Capacity : Typically not larger than 512GB for notebook size drives
Bootup Time for Windows 7 : Around 22 seconds average bootup time
Noise : There are no moving parts and as such no sound
Heat Produced : Lower power draw and no moving parts so little heat is produced
Failure Rate : Mean time between failure rate of 2.0 million hours
File Copy / Write Speed : Generally above 200 MB/s and up to 500 MB/s for cutting edge drives
Encryption : Full Disk Encryption (FDE) Supported on some models
File Opening Speed : Up to 30% faster than HDD
Magnetism Affected? : An SSD is safe from any effects of magnetism
Buy SSD if :
- You are willing to pay for faster performance
- Don’t mind limited storage capacity or can work around that then get an SSD.
HDD
Battery Life : More power draw, averages 6 – 7 watts and therefore uses more battery
Cost : Very cheap' only around $0.10 per gigabyte
Capacity : Typically 500GB – 2TB for notebook size drives
Bootup Time for Windows 7 : Around 40 seconds average bootup time
Noise : The spinning of the platters can sometimes result in vibration
Heat 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 1.5 million hours
File Copy / Write Speed : The range can be anywhere from 50 – 120MB/s
Encryption : Full Disk Encryption (FDE) Supported on some models
File Opening Speed : Slower than SSD
Magnetism Affected? : Magnets can erase data
Buy HDD if :
- You need lots of storage capacity, up to 2TB
- Don’t want to spend much money
- Don’t care too much about how fast a computer boots up or opens programs then get a hard drive.
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