Monday, 18 April 2011

The low down on memory...

If you've worked in support for any length of time, you'll have had a similar conversation to this at least once...

User: Hi there - My computer says it's low on memory
Support: No problem. How much memory does it have?
User: 250 Gigabytes
Support: (groans) No, how much physical memory does your machine have?
User: I told you, 250 Gigs.
Support: (sighs) That's not your memory, that's your hard disk...


User: Hi There - My computer says it's running low on disk space
Support No problem. How much space do you have free?
User: 4 Gig.
Support: Ok - delete everything from the temporary area.
User: Done!
Support: How much space fo you have free now?
User: 4 Gig.
Support: What? You've just deleted 30 Gigs of porn - you can't still have 4 Gig left...

...And so on...

Why do we receive these calls? Simply because there is confusion in the user's eye between Memory and Storage space, so let's address the problem with our little handy-dandy guide to all things Gigabyte...

Computers need to able to store information, otherwise, they simply couldn't function (and what would be the point in that). Computers need 2 basic types of storage space; storage that can be accessed almost instantly, and storage where the access time doesn't matter. With me so far?

Fast Storage is what we call Random Access Memory (RAM) or Physical Memory - that is, very fast, silicon chip storage space that the computer can use to store data. RAM is very, very fast and volatile i.e. the data only exists in storage as long as electrical power is supplied, which makes RAM ideal for storing data that the computer needs short term e.g. running programs, calculations etc...

In contrast, Slow Storage is used for data that needs to be non-volatile i.e. available to the system after power is removed. The most common form of Slow Storage is in the form of Hard Disk space, which we use to store the Operating System e.g. Windows 7, the programs we wish to use, and the data for those programs that we want to keep (such as photographs). Hard Disks are basically a collection of metal platters which store data magnetically.

Fast Storage is expensive, which is why you have quite a bit less of it than cheap and plentiful Slow Storage. The more Fast Storage you have, the faster your machine will run, but be warned - each machine has a limit on how much Fast Storage it can use.

You may have heard of Flash Drives, USB Sticks or Solid State Drives - these are all forms of Slow Storage that are either faster, more portable, or more reliable than normal Hard Disks. CD / DVD's are Slow Storage that are designed to be read only (you can't put data on them) or read many / write once in the case of DVD / CD writers.

So why the confusion? Simply because both types of storage are measured using the same scale - the Byte. 1 Byte can store a small amount of information (such as a character). 1 MegaByte = 1 Million Bytes (approximately) and 1 GigaByte = 1000 MegaBytes (also approximately), so as you can see, 250 GigaBytes is a lot of information!

Don't get me started on TeraBytes (1000 GigaBytes)... :)

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