INTRODUCTION
These days, no matter how much memory your computer has, it never
seems to be quite enough. Not long ago, it was unheard of for a
PC (Personal Computer), to have more than 1 or 2 MB
(Megabytes) of memory. Today, most systems require 128MB to run
basic applications. And up to 512MB or more is needed for optimal
performance when using graphical and multimedia programs.
As an indication of how much things have changed over the past two
decades, consider this: in 1981, referring to computer memory, Bill
Gates said, "640K (roughly 1/2 of a megabyte) ought to be enough for
anybody."
For some, the memory equation is simple: more is good; less is bad.
However, for those who want to know more, this reference guide
contains answers to the most common questions, plus much, much more.
THE ROLE OF MEMORY IN THE COMPUTER
People in the computer industry commonly use the term "memory" to
refer to RAM (Random Access Memory). A computer uses Ram to hold
temporary instructions and data needed to complete tasks. This
enables the computer's CPU (Central Processing Unit), to access
instructions and data stored in memory very quickly.
A good example of this is when the CPU loads an application program
- such as a word processing or page layout program - into memory,
thereby allowing the application program to work as quickly and
efficiently as possible. In practical terms, having the program
loaded into memory means that you can get work done more quickly
with less time spent waiting for the computer to perform tasks.
The process begins when you enter a command from your
keyboard. The CPU interprets the command and instructs the hard
drive to load the command or program into memory. Once the data is
loaded into memory, the CPU is able to access it much more quickly
than if it had to retrieve it from the hard drive.
This process of putting things the CPU needs in a place where it can
get at them more quickly is similar to placing various electronic
files and documents you're using on the computer into a single file
folder or directory. By doing so, you keep all the files you need
handy and avoid searching in several places every time you need
them.
THE DIFFERENCE BETWEEN MEMORY AND STORAGE
People often confuse the terms memory and storage,
especially when describing the amount they have of each. The term
memory refers to the amount of RAM installed in the computer,
whereas the term storage refers to the capacity of the computer's
hard disk. To clarify this common mix-up, it helps to compare your
computer to an office that contains a desk and a file cabinet.
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The file
cabinet represents the computer's hard disk, which provides
storage for all the files and information you need in your
office. When you come in to work, you take out the files you
need from storage and put them on your desk for easy access
while you work on them. The desk is like memory in the
computer: it holds the information and data you need to have
handy while you're working. |
Consider the desk-and-file-cabinet metaphor for a moment. Imagine
what it would be like if every time you wanted to look at a document
or folder you had to retrieve it from the file drawer. It would slow
you down tremendously, not to mention drive you crazy. With adequate
desk space - our metaphor for memory - you can lay out the documents
in use and retrieve information from them immediately, often with
just a glance.
Here's another important difference between memory and storage: the
information stored on a hard disk remains intact even when the
computer is turned off. However, any data held in memory is lost
when the computer is turned off. In our desk space metaphor, it's as
though any files left on the desk at closing time will be thrown
away.
MEMORY AND PERFORMANCE
It's been proven that adding more memory to a computer system
increases its performance. If there isn't enough room in memory for
all the information the CPU needs, the computer has to set up what's
known as a virtual memory file. In so doing, the CPU reserves
space on the hard disk to simulate additional RAM. This process,
referred to as "swapping", slows the system down. In an average
computer, it takes the CPU approximately 200ns (nanoseconds)
to access RAM compared to 12,000,000ns to access the hard drive. To
put this into perspective, this is equivalent to what's normally a 3
1/2 minute task taking 4 1/2 months to complete!
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Access
time comparision between RAM and a hard drive. |
MEMORY UPGRADE ON A PC: LIFE IS GOOD
If you've ever had more memory added to your PC, you probably
noticed a performance improvement right away. With a memory upgrade,
applications respond more quickly, Web pages load faster, and you
can have more programs running simultaneously. In short, additional
memory can make using your computer a lot more enjoyable.
MEMORY UPGRADE ON A SERVER: LIFE IS EVEN BETTER
Server performance has a huge impact on the performance of a
network: if a server is performing poorly, everyone on the network
"feels the pain." So, while a memory upgrade on an individual PC
makes a big difference only for the person who uses it, a memory
upgrade in a server has far-reaching effects and benefits everyone
who accesses the server.
To better understand the benefits of increasing memory on a server,
take a look at these benchmark results compiled by Mindcraft, an
independent testing organization specializing in quantitative
research. Mindcraft's study focused on servers running Windows 2000
Advanced Server, Sun Solaris 9.0 and Red Hat Linux 8.0 on both web
and DBMS server platforms. The objective of this research was to
reveal how server performance might improve incrementally by adding
more memory as an alternative to the installation of additional
processors.
In conducting it's research, Mindcraft discovered the performance of
Windows 2000, Solaris and Linux servers showed significant
improvement through the use of additional memory leading to
performance benefits of as much as 40% over servers with an
additional processor and no increase in memory. The performance
improvement could be as high as 1000% on dual processor DBMS systems
with the memory expanded from 512MB to 4GB.
CONCLUSION: MORE
MEMORY EQUALS BETTER PERFORMANCE
The Mindcraft research focused on the performance of Web and DBMS
servers, because applications response times in both of these areas
are among the most visible to the end user. Nobody likes having to
work with a slow web server and where database applications are
involved, the benchmark results clearly show that more memory
available means that the Operating System and DBMS can keep more
data in main memory, eliminating or reducing the frequency of
relatively slow disk accesses, which in turn lead to slower
applications response times.
