Ever since IBM introduced the hard disk drive back in late 50’s it has been the cornerstone of every desktop or laptop computers for well over half a century.
For the better part of the early 21st century, the traditional mechanical hard disk drive has been the default and often the only storage options for your computing needs. We have come a long way from magnetic tapes and floppy disks.
HDD vs SSD
|Feature||Solid State Drive||Hard Disk Drive|
|Performance – File Copy / Write Speed||Very Fast||Average|
|Moving Parts||None||2 or More|
|Noise||0 DB||27 DB|
|Capacity||Not Larger Than 1 TB||Typically Around 500 GB to 2 TB For Laptops|
|Boot Time||Around 10-13 seconds||Around 30 – 45 seconds|
|Failure Rate||Mean time between failure rate of 2.0 million hours||Mean time between failure rate of 1.5 million hours|
|Durability||More Durable||Less Durable|
|File Opening Speed||30% Faster than SSD||Slower than HDD|
The technology is time-tested and works its magic in every household with a computer. Hard disk drives have spinning disks called platters, where you read and write your data.
A Hard Disk Drive is made up of one or more magnetic circular disks(platters), a head used to read and write data on the platters, and a motor that spins the platter and control the actuator arm that moves the head.
It also has an I/O controller and some firmware for the interface with the system. The Platter is divided into concentric circles called tracks, these tracks are divided into sectors.
Every track and sector is given a unique number that is used as an identifier these numbers can be used as an address to organise and retrieve data. The Data is written on the nearest available address. The firmware is used to track where new data is written and identify any anomaly to correct any error.
Whenever the system wants to retrieve some data or write something the I/O controller will issue a command to the actuator to the desired address and the head gathers the data based on the presence or absence of charge at the given address. If the command is to write or update data the head changes the charge as needed on the specified track and sector.
Solid State drive is a relatively new technology which has grown leaps and bounds in the last few years. From being the talk of the town in research labs to become an option worthwhile to pursue while making buying decisions, it continues to add storage space and get cheaper at the same time.
A Solid State Drive, unlike traditional HDDs, uses integrated circuit assemblies like the NAND or NOR gates to store data persistently i.e the data is non-volatile and does not vanish when the power is cut off. You can think of a solid state drive as a large flash drive (pen drive) which you use with USB, as they both use the same underlying technology of Gates.
NAND Gates are generally used as they are cheaper to make. Here the floating gate transistors record a charge or the lack of it to store data. These gates are arranged in grids which are further grouped as blocks. The size of these blocks can be different for different cases but remember each row i.e. the grid corresponds to one page.
Like HDD the solid state drive also has a controller that does a lot of work including keeping track of the data and retrieving it.
When the system commands for retrieval or updation of the data the controller looks for the specific address and identifies the charge or lack of it thereof the read the data, updation is more complex in the case of SSD as the whole block needs to be refreshed for making any addition, so data from the old block is copied to other block and then the entire block is rewritten with specified changes after which the copied block is duly erased.
This is done when the drive is idle through a process known as garbage collection. There is a different process called TRIM which is employed, where TRIM tells the SSD which blocks are to be used for rewriting and which ones need to be skipped. This is done because any SSD has a finite number of blocks and repeated use of the same block may cause wear and tear.
Solid State Drives are relatively new and hence quite expensive. Although a lot of progress has been made with regards to the storage, SSD is still match for HDD. HDD can still hold up to 2.5 times more data than an SSD.
Hard Disk Drives are Cheaper and gives you more space, but are slower and use more power. SSD, on the other hand, is faster, less prone to wear and tear, energy efficient but expensive.
So let your needs decide your buying decision. If you are a power user go for SSD, if you don’t worry about a millisecond and are one who does not drop his laptop, HDD will work fine by you. And you can also go for the best of both worlds with a hybrid. SSD for gaming and complex computing and HDD for more mundane stuff. The choice as always is yours.