What is a 'Cache'?

Question

I am thinking about buying an External Hard Drive and it says (for example) '16Mb Cache'. What does this mean?
Thanks

Answer 1

In computer science, a cache (pronounced /kæʃ/, like the English word cash) is a collection of data duplicating original values stored elsewhere or computed earlier, where the original data is expensive (usually in terms of access time) to fetch or compute relative to reading the cache. Once the data is stored in the cache, future use can be made by accessing the cached copy rather than re-fetching or recomputing the original data, so that the average access time is lower.

Answer 2

The other answers above are correct. I just wanted to add in your particular question, the 16Mb Cache means there are 16Mb of RAM on the hard drive. The Drive prer-fetches data it thinks you are going to use for faster access. That is how they increase data retrieval speed. CPU's use cache memory for the same reason, the CPU's now have memory on the chip to pre-fetch programming instructions. With the 486 (Rember those?), Cache was really fast (in relation to system memory). It had a 15 or 10 millisecond access time, as opposed to 80 milliseconds for system memory. The Packard Bells were notoriously slow because they did not add this memory to cut costs.

-Dio

Answer 3

Hard disk cache's are an important element of a computer system whose primary aim is to increase overall system performance by saving data in faster banks of RAM.

Hard drives have a cache built in to hold data that is being written to or read from the hard disk. The purpose of doing so tries to reduce the number of occasions in which data has to be physically written and read from the hard disk platter. By retaining recent data within the cache performance is increased as this memory is much faster and saves time on repeat recalls.

The other primary function of a cache is to try to match speeds between devices so that the faster device is not held up, or isn't held up as much. In the case of a printer the cache stores data sent to the printer from the system where it is held until the printer is able to print it off. This enables the system to continue other tasks whilst the printers cache holds onto the information.

Cache's exist also in the computers operating system where a specified amount of RAM is set aside for storing repeatedly used data to again reduced the amount that has to be written on to the hard drive. Users can adjust their system cache but must make sure that they do not allow too much RAM to be used in this manor and hence cause less RAM to be available for programs which in turn have to use hard disk memory thus defeating the intent.

Hard drives often now have 2mb caches which is a benefit to system performance, faster drives are commonly fitted with 8mb caches which again further increase performance.

So 16mg cache would make this Hard Drive you saw very fast WOW!! Buy it!!

Answer 4

Cache is the temporary memory used to speed up the read process when the source is relatively slow.

Browsers use cache (store data) so pages load faster when they are loaded the second time. Cache isn't as useful with broadband connections, but very useful with dialup.

Generally speaking, the more cache, the faster your hard drive usually is. It's not the only factor, but it's one you should certainly consider. How much of a performance increase depends on the activity you're doing. See my browser explanation above for when cache may help.

Short Answer:
Cache improves performance, more is better.

Hope this helps,
Ken

Answer 5

It means that after your programs read data from the disk they also store it in an internal memory ("cache") of the disk drive. In this case the memory is 16 Megabytes long. If the program needs to read the same data again soon the data from that cache memory will be used immediately instead of waiting for the disk to be read again. On the average it means that programs can get the data they need more quickly.

Answer 6

As an analogy, you've just boiled the kettle to make yourself a cup of tea. You can either go across to the local shop and fetch a bottle of milk, or you can use the milk that you've already got in your fridge. (The milk in the fridge, in this instance, would be the cache ... pronounced 'cash'. It's closer to hand, hence quicker to retrieve.)

Answer 7

It is a place on your computer that stores information temporarily. When you access a website, it is saved to your computer’s cache so that when you visit that page again in the future, the page appears on your screen faster because it is pulling saved content from your computer instead of a server out in cyberspace.

Answer 8

In computing terms, it's a temporary pre-load space for data.
More generally:

cache noun 1 a hiding-place, eg for weapons. 2 a collection of hidden things. verb (cached, caching) to put or collect in a cache.
ETYMOLOGY: 19c: French, from cacher to hide.

Answer 9

A method of storing data for quick retrieval.

Answer 10

in one word = it means = storeage