By Ken Lee

Solid State Drives SSD vs. Hard Drives HDD

For many years solid state drives have been reserved for technology enthusiasts, hardcore gamers and those with deep pockets. The performance advantage of SSDs over traditional, spinning-platter hard disk drives, or HDDs, has never been a point of contention. SSD's transfer rates typically double or triple the speed of their mechanical counterparts. However, the high retail price for even low-capacity SSDs prevented the average computer user from experiencing the benefits of an SSD.

As the cost per gigabyte for SSDs has come down in recent years we are finally seeing SSD prices straddling the line of affordability and consumers and manufacturers have taken notice, and you should too. In addition to becoming affordable, added features and improved technology have SSDs making a strong case to replace the aging HDD in your computer or laptop.


It is a common fallacy that SSDs are less reliable than HDDs. This is actually pretty far from the truth. In 2010, the percentage of component returns to retailers was very close between the top 5 SSD manufacturers and top 5 HDD manufacturers, about 2-3%[1].  So we know that SSDs aren't being returned at a higher rate than HDDs.

This misconception may be the result of SSDs growing pains through its early years. Early SSD adopters were plagued by issues like poor firmware, degrading flash memory and other issues typical to new technology. This resulted in an initial negative response from the tech community which may be continuing to haunt SSDs, even though the reliability of SSDs has become better than HDDs on several levels.

Fundamentally solid state disks are more reliable because SSDs do not contain any moving parts. There are no read heads, actuator arms or spinning platters that can break down in an SSD. SSDs can be moved around freely while in use and have a higher tolerance against shock and vibration than HDDs. In a mechanical HDD platters spin at thousands of rotations per minute, and any shock or vibration can cause data to become corrupted or a mechanical component to malfunction.

When a mechanical hard drive with spinning platters crashes it often results in physical damage to the platters which store data. Physical damage to these platters could cause data to be lost permanently. SSDs do not suffer from this vulnerability. Typically if a SSD crashes, it usually occurs with an electronic component like a transistor or capacitor which may cause the drive to be inoperable, but the memory should remain completely intact and recoverable.

New Technologies

As with any new technology, SSDs experienced their fair share of growing pains as they matured. And like with so many problems that occur with new technology, these problems were fixed using technological innovations.

-          Native Command Queuing (NCQ): Originally designed to increase SATA HDD performance by optimizing the order in which read/write commands are executed, NCQ reduces latency on mechanical drives by grouping commands that would be read/written to the same area on the disk. However with solid state drives, since there are no moving parts, there is extremely low latency and the opposite occurs. NCQ ensures that a SSD has commands to process while the host system is processing CPU tasks.

-          TRIM: NAND flash memory cells are grouped into 4kB pages, which are then further grouped into 512kB blocks. Cells can only be written to if they are empty, and though write operations can occur on the page level, erase commands affect entire blocks. So in order to overwrite a page, the contents of the entire block have to be moved to cache before the block can be erased, and then rewritten. This causes a dramatic decrease in write performance when pages need to be overwritten. The TRIM command allows the SSD to handle garbage collection overhead in advance.

Power Consumption

Without any moving parts, SSDs provide an enormous advantage over HDDs in power efficiency. This is especially beneficial for road warriors who are looking for ways to squeeze more life out of their laptop battery. Although an SSD actually increases system power consumption, since the CPU and memory utilization rises in response to increased I/O activity, an SSD based system will always finish operations faster and ultimately will allow you to go longer without having to plug in.


At the end of the day, price is what your typical consumer looks at when looking to update their computer. However you cannot base the total cost of an SSD on price per GB alone. For businesses, upgrading to SSDs in your workstations means faster system boot up times which allows your employees to spend less time waiting for their systems to start and more time working. Then there is time saved waiting for applications to load, reduced deployment time and less downtime for IT support. When you factor in all these variables, you can see how an SSD is an investment that pays off over time.

The future of data storage is solid. Although the technology has needed time to work out the kinks, we are now witnessing an evolution in the way we process data. The time of mechanical, spinning hard drives is drawing to an end, and I for one welcome the change. Wide spread adoption of solid state drives will bring computing advancements to the next level and you would be well advised not to get left behind.

[1] Marc Prieur. "Components Returns Rates,", 2010 (December 25, 2010)

Written by Ken Lee — October 31, 2012

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