Colorado State University

SSD, HDD, and Hybrid Drive comparison

You may have noticed that, recently, CNSIT has been pushing to install SSD (Solid State Drives) instead of the traditional HDD (Hard Disc Drive) or even the Hybrid drive system.  This article will explain why we have made this decision and show that the SSD format is not only faster, but also considerably more reliable as well.

Description of Hard drive formats

To get a better understanding of the differences between the three formats (SSD, HDD, and Hybrid), you need to know what components are inside each.

1) SSD-A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies as memory to store data persistently. It is also sometimes called solid-state disk, although SSDs do not have physical disks. SSDs may use traditional hard disk drive (HDD) form-factors and protocols such as SATA and SAS, greatly simplifying usage of SSDs in computers. Following the initial acceptance of SSDs with HDD interfaces, new form factors such as the M.2 form factor, and new I/O protocols such as NVM Express have been developed to address specific requirements of the Flash memory technology used in SSDs.  SSDs have no moving mechanical components. This distinguishes them from conventional electromechanical drives such as Hard disk drives(HDDs) or floppy disks, which contain spinning disks and movable read/write heads.

2) HDD-A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electromechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces.  Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile storage, retaining stored data even when powered off.

3) Hybrid drive-A hybrid drive (solid state hybrid drive – SSHD) is a logical or physical storage device that combines a faster storage medium such as solid-state drive (SSD) with a higher-capacity hard disk drive (HDD). The intent is adding some of the speed of SSDs to the cost-effective storage capacity of traditional HDDs. The purpose of the SSD in a hybrid drive is to act as a cache for the data stored on the HDD, improving the overall performance by keeping copies of the most frequently used data on the faster SSD.

So, why choose SSD instead of a HDD?

1) Speed- An SSD has access speeds of 35 to 100 micro-seconds, which is nearly 100 times faster than a traditional HDD (Which have access times of 5,000 to 10,000 micro-seconds). This faster access speed means programs can run more quickly, which is very significant, especially for programs that access large amounts of data often, like your operating system.

2) Reliability- The SSD has no moving parts. It uses flash memory to store data, which provides better performance and reliability over an HDD.  One major drawback of an HDD is the susceptibility to data loss and overall device breakdown due to drops and shudders. This drawback stems from the mechanical or movable parts inside a hard disk drive. Because an SSD has no moving or mechanical parts, it is more durable to drops and shudders thereby making it more resilient against data loss caused by physical or external trauma. This is another worthy advantage of a solid-state drive especially when taking into consideration mobile computing.  One study (https://www.backblaze.com/blog/how-long-do-disk-drives-last/)  on hard drive reliability reported:

The chart below shows the percentage of drives at Backblaze that are still alive at different ages:

• For the first 1.5 years, drives fail at 5.1% per year.
• For the next 1.5 years, drives fail LESS, at about 1.4% per year.
• After 3 years though, failures rates skyrocket to 11.8% per year.

So, after 6 years a standard hard drive has about a 50% chance of failure, while a SSD drive (in theory) should last around 20 years.

3) Power consumption- An HDD consumes more power because it relies on the rotation of the magnet-coated metal platter for reading and writing data. An SSD has no moving parts and it does not require mechanical work to become operational. This low power consumption gives solid-state drives another advantage. This means that an SSD is suitable for energy efficient computers and consumer electronic devices.

4) Heat- Because there are no moving parts and due to the nature of flash memory, the SSD generates less heat, helping to increase its lifespan and reliability.  With moving parts comes added heat which can slowly damage electronics over time, so the higher the heat, the greater the potential for wear and damage.

5) Noise- With no moving parts, SSD generates no noise. With the spinning platters and moving read/write heads, an HDD can sometimes be one of the loudest components in your computer.

6) Magnetism- SSD is not affected by magnetism.  Because a hard drive relies on magnetism to write information to the platter, information could be erased from an HDD using strong magnets.

How about a Hybrid?

Hybrids essentially try to make the best of both worlds, and in some instances (for instance: you need a large (over 2TB) hard drive) even make sense, however, it’s important to remember two things:

1) If either part of the hybrid drive stops working, the entire device fails. Data recoveries, in general, tend to be more complicated for a hybrid system compared to either an individual SSD or HDD. Both the SSD and HDD are needed to have the best chance to complete a successful data recovery.  Long-term reliability is unknown, since these devices have not been in general circulation for more than a few years.

and:

2) A hybrid drive will run considerably faster than an HDD but slower than a pure SSD.  It will have more storage capacity than a pure SSD, but maybe not as much as some of the largest size HDDs on the market today.

Conclusion:

Because of all the reasons listed above, CNSIT has decided that all future machine purchases will have SSDs installed and to install SSDs in any “problem” machines that we currently can.