What are SSDs? SSD vs HDD

I'm sure you all remember seeing something like this:

A Western Digital mechanical hard drive

For storage of data we have been using mechanical hard disk drives since decades

These days you may come across the term "SSD" drives so what exactly are these SSDs?

In layman terms a SSD is a storage device that is much faster than a HDD and has no moving parts.

SSDs give you a huge speed boost when compared to a HDD and are also more reliable.

SSDs use NAND flash chips for data storage and have larger caches and so have low access times.

An SSD looks like this:

A SATA II OCZ SSD

To give you an idea of the magnitude of an SSD's speed let me give you an example

I recently upgraded my PC and put in a SSD in place of my HDD and earlier the PC used to boot into windows in about 30 secs and after the upgrade it booted in just 7 seconds!

SSDs still have not replaced Hard disk drives(HDDs) because of the following reasons:

1. They are expensive compared to HDDs

For example a good 60gb SSD would cost around $90(4500INR) while you could get a 1 terabyte HDD for around the same price.

2. They do not come in very large capacities - SSDs usually have small capacities. The largest SSD that a consumer would buy is only about 480GB and it would also cost a fortune while a 3 terabyte HDD can be bought for much less. There are industrial grade SSDs such as the OCZ Revodrive that use the PCI-e interface and have about 1.5 terabytes of storage but if a normal person wished to buy it then he would have to sell his house first!

Below is a benchmark result comparing an Intel SSD and a HDD

You can see from the benchmark above that an SSD is much faster during a random seek and a sequential read but is only a bit slower at data writing. New SSDs have further improved upon this.

In the end I would say that for now just get a 60gig SSD like the OCZ Agility or vertex series for the OS and keep a good ol' HDD for other data.