- What is SSD ?
Knowing SSD & HDD more advanced– A solid state drive (SSD) is an electronic storage drive built on solid state architecture. SSDs are built with NAND and NOR flash memory to store non-volatile data and dynamic random access memory (DRAM). A SSD and magnetic hard disk drive (HDD) share a similar purpose.
A SSD is also known as a solid state disk (SSD) or electronic disk drive.
- What is HDD?
A hard disk drive (HDD) is a non-volatile computer storage device containing magnetic disks or platters rotating at high speeds. It is a secondary storage device used to store data permanently, random access memory (RAM) being the primary memory device. Non-volatile means data is retained when the computer is turned off.
A hard disk drive is also known as a hard drive.
- How does an SSD work?
Knowing SSD & HDD more advanced – A simple USB flash drive (or thumb drive) is an example of solid-state drive technology. An SSD is a larger, more complex device that aggregates pools of NAND flash storage, the type of storage also found in MP3 players and digital cameras. Unlike RAM, which doesn’t retain data when the machine shuts off, SSD flash memory is non-volatile, which means data is retained whether the device is powered on or not.
With SSDs, every block of data is accessible at the same speed as every other block, no matter the location. This makes SSDs inherently faster than hard drives, where platters are spinning and drive heads are moving to the right location.
With HDDs, large files can be broken up and tucked into unused nooks and crannies of the drive, and data can be easily updated in place. This allows for efficient use of the total drive capacity. On the other hand, scattered data obviously takes longer to locate, which is why defragmenting a hard drive has become a standard part of device maintenance.
SDDs have a different and bigger problem – SSDs can only write to empty blocks. That’s okay when the SSD is new and all the blocks are empty. But over time, as blocks get filled up, overwriting data becomes an issue, because the only way an SSD can update an existing page is to copy the contents of the entire block into memory, erase the block and then write the contents of the old block in addition to the new data. If there are no empty blocks available, the SSD must scan for blocks marked for deletion, but not yet deleted, erase them, and then write the data to the now-erased page. Over time, as the SSD fills up, writing to the drive becomes more complicated and slower.
- How does a HDD work?
Knowing SSD & HDD more advanced – If you were to open your hard drive, which would immediately void your warranty and potentially damage it, you would see something like the image below:
A hard drive consists of the following:
Magnetic platters – Platters are the round plates in the image above. Each platter holds a certain amount of information, so a drive with a lot of storage will have more platters than one with less storage. When information is stored and retrieved from the platters it is done so in concentric circles, called tracks, which are further broken down into segments called sectors.
Arm – The arm is the piece sticking out over the platters. The arms will contain read and write heads which are used to read and store the magnetic information onto the platters. Each platter will have its own arm which is used to read and write data off of it.
Motor – The motor is used to spin the platters from 4,500 to 15,000 rotations per minute (RPM). The faster the RPM of a drive, the better performance you will achieve from it.
When a the computer wants to retrieve data off of the hard drive, the motor will spin up the platters and the arm will move itself to the appropriate position above the platter where the data is stored. The heads on the arm will detect the magnetic bits on the platters and convert them into the appropriate data that can be used by the computer. Conversely, when data is sent to the drive, the heads will this time, send magnetic pulses at the platters changing the magnetic properties of the platter, and thus storing your information.
- HDD or SSD?
A traditional hard disk drive (HDD), sometimes referred to by its abbreviated names hard disk or hard drive, is a form of magnetic mass storage used primarily in computers, but also in portable music players, video cameras, DVD players, and video game consoles etc.
Solid state drive (SSD) technology can also be used as hard drives, where data is stored on an array of chips attached directly to the circuit board. These are also found in music players, but also in mobile phones, tablets, and many modern smart devices.
- SSD vs. HDD in the enterprise
SSDs have a number of advantages over HDDs that can help offset the difference in sticker price. SSDs are quiet. They don’t vibrate, which improves reliability. If dropped, a hard drive might get damaged; not so with an SSD. They use less power and generate less heat, which can add up to big savings in a large data center scenario. They are also smaller and more powerful than HDDs, so data centers can pack more storage into less space. And, of course, there’s the speed advantage.
Since HDDs have a massive installed base of customers who basically feel that disk drives are “good enough,” the decision to go with a new and different technology requires that companies build a solid business case.
Companies need to conduct a detailed cost/benefit analysis to determine whether a move to SSDs make sense. One deployment approach would be a slow migration where SSDs would be a requirement in new servers and storage devices. Another approach is to use SSDs exclusively for “Tier 0” data in a tiered data storage scenario. Tier 0 data is transactional data requiring high performance, such as in financial or ecommerce applications.
Other enterprise use cases for SSDs include ruggedized notebooks or laptops, applications where boot time is important, the editing of large media files like video and audio, cache drives and database servers.
At the same time that enterprises are thinking about SSDs vs. HDDs, it’s important to note that the total volume of data is exploding, so most companies will continue to buy both types of drives for a very long time. In fact, IDC predicts that even as SSD sales volumes increase, solid-state drives will still only amount to 20% of total market share in the enterprise by 2025.[YUSUF TI 2017]