So what this does is it means you can have four servers sitting in a cluster
and now you don't have to worry if one of your service fails because if one of
your servers fails, you still have three other servers that are functioning
completely fine, that your users can go to. Again is very important like with
active directory clusters in a windows world you know in order to be able to
login to a windows domain you have to be able to connect with active directory
controller.
If you only have one active directory controller and that fails,
then when you try to authenticate nothing can happen. If you haven't anyc
luster and that one server fails then the system will just route you to another
active directory server that is still up and running and can authenticate you.
Again these clusters are normally used in database environment and this is very
important especially in the web world.
We just talked about web applications,
most web applications store their data in databases now, which is generally my
sql databases. So you know when you create a document or you create a blog post
like you use WordPress and create a blog post, that blog post the information
actually stored in a database. So normally it gets stored in a database and if
there is only one server that one server fails, nothing happens but if you have
my sql cluster if one server failes your blog stays up and running because the
information will simply be pulled from a different server with in the cluster.
So this is clustering basically what is clustering is again you can have
different types of hardware so this can be a xeon processor or that can be a
Pentium processor or that can be a Celeron processor or that clould be an AMD
processor. These do not have to be the same hardware. You can sometimes have
different operating systems depending on your clustering. Then you know you can
have windows 2008 here or Windows 2003 here and some other versions here.
The
main thing is the application that is installed on the operating systems,so
again my sql is installed on a Windows 2000 Server which is installed on some
AMD processor with a gig of ram, now within my sql, you will create
configuration to create this cluster and create replication again replication
is when these different databases talk to each other and basically copy and
paste or exchange information .So what if a record is change in this my sequel
database the replication is when it sends that change out to all the other
databases within the cluster. So that is clustering, it is a very important
concept when we’re talking about cloud computing like I say because you may not
realize that the average person may not realize it, but a lot of the stuff you
do online probably 90% of the stuff you do online has some components that puts
data or has data in a database so all the data you store you know it's best
that you put into one of these cloud environments and these are cluster
environments.
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