Hard Disk Drives vs Solid State Drives

Hard Disk Drives and Solid State Drives are storage mediums meant for large long lasting storage.

Performance

Hard disk drives provide faster throughput, but solid state drives provide faster seek time. Generally, a SSD's seek time overcompensates for it's lower throughput.

Robustness

Hard disk drives can lose data if they receive a large enough impact, though enterprise and gamer grade hard disks can be rated at over 100Gs. In the event of shock, platter damage may occur and segments of data rendered irrecoverable. Although solid state drives do not have moving parts and are not as susceptible to shock at low levels, when damaged, the whole drive may be rendered inoperable due to the cascading effects of solid state's high density.

Since solid state disks have no moving parts, they are not prone to mechanical failure when only used as read only media. However, when written to, flash based solid state drives degrade at an accelerated rate. DRAM based solid state drives do not exhibit this, while hard disks degrade at the same rate as in when reading. When flashed based solid state drives are constantly written to, they may fail within several days. However, at actual usage rates, failure commonly occurs after one to two years of usage.

Storage Capacity

Currently, hard disk drives provide greater capacity than solid state drives. Consumer grade hard drives are available in capacities of up to 3 TB, and although high-end enterprise grade SSDs can reach 2 Tb in size, they remain prohibitively expensive.

Data Longevity

HDDs use magnetically charged platters to store data, and will retain this charge unless acted upon by a strong electromagnetic force. Some SDDs will eventually leak electrical charge and zero all data over the course of decades.

Price

While SSD's have been available since the mid 50's, in the form of magnetic core storage, their price has only recently decreased to become competitive to conventional hard drives. Even so, the magnitude of difference between price restricts SSD to high performance storage (main OS drive) and not mass data storage (secondary data storage).

Secure Data destruction

SSDs employ wear levelling as they have a limited number of writes per data storage area of the drive. To compensate, most employ firmware to ensure the drive degrades evenly, directly inhibiting attempts to overwrite existing data, leaving traces of data. Although possible, the use of forensic wiping tools will significantly degrade the state of the drive

HDDs do not suffer from these effects as they are not limited by writes.

Both HDDs and SSDs will succumb to physical data destruction methods such as Thermite.