Solid State Storage
Computer Science: Cambridge International GCSE, topic 1.3.10
How Solid State Storage Works
Solid state storage is an increasingly popular alternative to other storage media. It is often also referred to as flash storage or flash memory.
Storing a bit
- Solid state drives are made of flash memory.
- Flash memory stores the value of each bit in a semi-conductor chip.
Accessing data
- Data can be accessed randomly. This means that any piece of data can be accessed in a constant amount of time.
- This is achievable because there are no moving parts.
Reliability
- Solid state drives (SSDs) are robust. They have no moving parts, so they are not easily damaged by shocks.
- SSDs have a limited number of read/write cycles. After a certain number of re-writes they will stop working.
Properties of Solid State Media
Solid state media has a lot of benefits, but it isn't the best media in all scenarios.
High speed
- Solid state media tends to have very fast read/write times.
- Some solid state media has slower access time. For example, USB sticks.
High cost
- Solid state media has a higher cost-per-GB than magnetic media.
- Solid state drives (SSDs) do not last as long as hard disk drives (HDDs), so the cost can often seem restrictive.
- Some people choose to pay more for the increase in performance.
Good capacity
- SSDs have a good capacity, but not on the scale of optical or magnetic media.
Good reliability
- Solid state media is very reliable and robust:
- It rarely fails (until read/write limit is hit).
- It is not easily damaged by shocks.
- Once the read/write cycles are used up, then the drive will fail.
Test yourself on Solid State Storage
A home computer user's solid state drive (SSD) has failed. They are trying to find out why this has happened, but the only thing that they have done differently recently is use virtual memory. Why has their SSD failed?