SSD vs HDD

We are aware of different kinds of memory, classified as volatile and non-volatile. Volatile is a kind of memory which looses it's stored contents when power is removed. Non-volatile is kind of memory which retains it's contents even when power is removed. Hard drive in your system is one kind of non-volatile memory. Hard disk can be of two types, either HDD or SSD. Many of us are unaware of the primary differences between the two types.

Before going to discuss more about those types, let us first know the basic purpose of storage devices on systems:

• Used to boot the system
• Store your personal files
• Store multimedia data
• Store your applications
• Store your operating system 

HDD (Hard Disk Drive):

Hard drives have a rotating arm with read/write header. The header moves over a metal platter with magnetic coating for read/write operation. There are several sizes available for HDDs. For example 2.5" for laptop and 3.5" for desktop. These drives moves at a speed of 5400 or 7200 or 15000 rpm. Faster the rotation speed, faster is the read or write operation. HDD used serial interface to communicate with the processor initially, then it moved to IDE, then SCSI and SATA now-a-days. These days we have HDDs with capability up to 4TB (Tera Bytes). The 2.5" inch drives are available in sizes up to 2TB and 3.5" drives up to 4TB.

SSD (Solid state drive):

A solid state drive is made from solid state devices like transistors which have charge carriers. SSD is basically a interconnected flash chip architecture which is mostly used in netbooks and ultrabooks. These SSDs can be mounted on mother board, connected as like HDD or slotted into a PCIe slot. SSD is basically a NAND flash .with read and write cycles faster as compared to a normal thumb drive. Processor reads and writes data as per the addressing and speed of operation of SSD directly gets effected by that. As like HDD, these are available in 2.5" inch size and up to size of 1TB storage capacity for that size. But it is very rare that you see that huge storage capacity with SSDs. Adding to this there is mSATA short term for mini-sata which fits into mini PCIe slot of a laptop.

The main differences between HDD ans SSD are tabulated below for quick reference:

By seeing the above table, we can tell that the choice of storage must be SSD. But SSD has to go a long way to replace HDD in environments like servers, large multimedia storage requirements.

the below figure shows the noise recording near a SSD and HDD:

Other than SSD and HDD, there are other variants like hybrid drives and multi-drives.

Hybrid drives:

• Flash chipsets on the same HDD making a combo kind
• Flash chips are used only for booting and application storage
• Flash chips are not directly accessible by user for storage and programming
• System boot speed is increased because of flash and applications can be launched quickly

Multi drives:

• One approach is to use both HDD and SSD in  a system
• Again SSD is only for booting and application storage
• HDD for files storage
• This manages cost as well as speed in one attempt
• Only problem is to integrate both on a space constrained system

Systems with SSD:

• HP Elite Book Revolve 810 has 128GB SSD. HP Elite Book is basically a ultra-flexible laptop.