Short for “solid-state drive.” A type of storage device, with no moving parts and typically based on flash RAM, that emulates the function of a conventional hard drive as a data storage medium. Characteristics of SSDs include a small amount of DRAM, which is used as a cache (similar to the cache found in hard disks), and in some cases a power source to maintain storage when the device’s power is turned off (often a capacitor or battery).
Advantages of SSDs over conventional hard drives include:
- No spin-up time (faster starts)
- No moving parts (better reliability)
- Consistent read performance (location of data on drive is irrelevant)
- No physical latency (no read or write heads to physically move)
- Low power consumption
- Low heat generation
- Extreme shock, temperature, and vibration resistance
- Higher data density (smaller, lighter form factor)
- Low incidence of failure during read or write (better reliability)
At this writing, disadvantages compared to conventional hard drives include:
- Higher cost per gigabyte
- Smaller maximum capacities
- Slower write performance than read performance
- Some security issues with re-writing encrypted data
- Limited lifespan and number of write/read cycles
- Due to “wear leveling,” performance can degrade with on-going use
Expect these disadvantages to diminish radically as the technology continues to improve.