Hard Drives vs Solid State Drives

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Hard Drives vs Solid State Drives

Solid State Disks otherwise known as SSD have begun to enter the computer marketplace as a replacement for hard drives.  Many people have dealt with this type of technology in other forms such as thumb drives, mp3 players, and many other small devices.

With this being a new technology, it is still very expensive and storage capacities are nowhere near magnetic drive capacities.  Many computer builders will tout the benefits of such drives from faster access times to lower power requirements.  Lets go over the pros and cons of each technology.

Hard Drive
SSD

Pros:

Low cost per GB 
Available everywhere 
Tried and true tested technology

Faster startup, no spin-up required 
Near instantaneous random access 
No noise 
Lower power requirements 
Better able to endure shock and vibration.

Cons:

Has reached the limit of its transfer speed 
Very sensitive to vibration and shocks 
Uses more energy and produces more heat

Prices are extremely high per GB 
Small capacities (Max 256 GB) 
Limited number of write cycles 
Slower random write speeds

We here at AVADirect like to make sure what we are recommending to our customers is exactly what these manufacturers are stating as their product specifications.  We decided to run our own tests to see if these SSDs were better and faster than a normal hard drive.  Below you will find what the manufacturers state about their products.

HDD
SSD

Manufacturer:
Western Digital
Super Talent

Size:
160 GB 
64 GB

Speed:
7,200 RPM
N/A

Buffer Size:
16 MB
N/A

Seek Time:
8.7 ms
0.1 ms

Transfer Rate:
70 MB/s
57 MB/s

MTBF:
1,000,000
>1,000,000

Operating Power:
10.75 Watts
1 Watt

Shock Rating
65 G / 250 G 
1500 G

Price:
$65
$1400
From these specs, you can see that the SSD really shines at seek times.  That much change in seek times equates to the HDD being 8600% slower than the SSD.  However, the HDD posts a faster transfer rate than the SSD.  This is because the HDD has a large and fast buffer, which helps the drive store and send data when the actual hardware is at its max.  
Lets move on to the real world results using EVEREST Disk Benchmark.

Hard Drive Disk Performance Click for large picture

Average Read Access
Buffered Read
Linear Read
Random Read
Averages

Solid State Disk Performance Click for large picture

Average Read Access
Buffered Read
Linear Read
Random Read
Averages

Buffered Read
Buffered reading is exactly what it sounds like, reading the data using the drive's built in data buffer.  The drive is requested to transfer a large data chunk and it moves this data in smaller pieces more manageable instead of moving the smaller pieces bit by bit.  This is where the HDD really shines as that buffer memory is faster than the SSD memory cells.  Also, that buffer can also act like a cache where previously read memory can be retrieved directly from the buffer, instead of being read again from disk.  This can greatly increase transfer speeds.
Random Read
Random reads are taking from different locations inside the physical disk.  This means that for the HDD, the mechanical components have to search for that specific data.  This takes time to do as the HDD disk needs to spin to the correct location while the arm inside needs to move to correct track.  SSDs do not have to search for the data.  A linear read and a random read are the same to a SSD drive.
Linear Read
A linear read is a read that does not have data in different places on disk.  All the data that is needed is in a continual line.  This means that a mechanical HDD does not need to stop reading, move its reading arm, and then begin reading again.  The different linear reads above are because the HDD reads data at different rates based on where the read head is located at.  When it is farthest away from center, the linear speed of the disk is greater than the inside of the disk.  This translates to faster read speeds when away from center and slower read speeds when closer to center.
Conclusion
While the HDD did pull ahead in certain aspects, it only did so under the most optimal of conditions.  It also was 15% on average away from its rated transfer speed of 70 MB/s.  The SSD performed the same no matter what kind of read was needed and was spot on with manufacturer's rated speeds.
While based on performance to price ratio, I just cant help but squirm when I look at the price of the SSD.  Sure overall speeds may be higher by 10% or more but the price difference is close to 2000%.  As of right now, I do not see a reason to switch to SSD until the price drops drastically.
Although based upon the other aspects besides price, size, and performance, SSDs can improve the overall enjoyment of a laptop.  The battery life will be longer because the SSD uses less power.  The drive will be much more resilient to breaking from a fall because there is no moving parts.  But unless you absolutely need those features, a hard drive is still my recommendation.
Don't get me wrong, I truly believe that SSDs are the future, but the technology has yet to mature.  I expect to see these drives competing directly against each other in less than a year.

Edited by MattSlagle - 18 Apr 2008 at 5:56pm