Have you ever heard the terms, head crash or stiction? Better yet, have you ever experienced either of them? These terms are just two of the unhappy occurrences associated with mechanical disks. What if disks didn't spin? What if there were a way to create rewriteable storage in such a way that there were no platters, no spindles and no heads? You'd have a solid state disk with no moving parts. Solid state disks (SSDs) are all the rage for server vendors, SAN vendors, and appliance manufacturers. Why? Not because they're cheap -- they're not. SSDs have several advantages over traditional mechanical (spinning) disks. Here are 10 of the most frequently quoted advantages of SSDs over mechanical disks.
1. Life Expectancy
Mechanical drives have an average life expectancy of three to five years. Many fail long before the lower end of the average, and few last beyond the upper end of the average. At three years, you should seriously consider a refresh. At five years, you're skating on ice so thin it's really just very cold water. Alternatively, SSDs have life expectancies reaching into decades, although trusting the 1 million to 2 million hour SSD expectancy claims seems as ridiculous as the 500,000-hour claims of mechanical drive manufacturers. Expect your SSDs to last two to three times longer than mechanical drives.
Since SSDs have no moving parts, their access and seek times are many times faster than those of their mechanical counterparts. Mechanical drives have high-burst speeds, but their sustained speeds are unimpressive by SSD standards. However, write performance is not significantly different between the two technologies*. Therefore, read and access performance-heavy workloads will benefit from SSDs, while workloads that are write-intensive would do as well with the less-expensive standard disks.
3. Physical Size
You usually see standard disks in 3.5 inch or 2.5 inch formats, but SSDs take small form factor two steps further with 1.0 inch and 1.8 inch disks. These smaller sizes allow manufacturers to build smaller appliances, mobile systems and blades that occupy very little space. With rack space at a premium, that's a very good thing.
4. Shock Resistance
SSDs are a good choice for mobile systems due to their resistance to drops, bumps and g-forces. Such forces don't often act on standard concrete and steel data centers, but what about mobile ones -- mobile data centers such as those used by ground military forces, aboard ships, on aircraft or at trade shows? Movement can have devastating effects on mechanical drives, especially during write events. SSDs, again having no moving parts, aren't affected by mobility and are well-suited to such physical abuse. SSDs can withstand up to 1,500 g during operation or 25 times that of a standard drive.
5. Failure Rate
Any mechanical or electrical device can, and will, fail, but your chances are greater for failure when those parts are in motion. Mechanical disks are not particularly robust and can fail at any time, as one manufacturer's representative once stated, "Any time between 15 seconds and 10 years." While SSDs haven't reached the adoption level of mechanical drives, manufacturers estimate very low failure rates compared to standard technology.