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NOTE The second half of this chapter talks about virtualizing your data storage.
Use Caution
Although the ideal for reducing power usage and hardware costs seems to be consolidating
and virtualizing everything onto a lone server, that’s really a bad idea. Yes, it’s cheaper and
there’s less environmental impact, but you also run the risk of having an extended outage or
losing everything should the server fail.
The easiest way to protect yourself is to ensure that your servers exist on more than one
physical server, as shown next.

HTTP DHCP
FTP RADIUS
DNS LDAP
Mail

DHCP HTTP
RADIUS FTP
LDAP DNS
Mail
In the event of a physical
server’s failure, locating
the virtual servers on
backup devices can keep
the services running.
If you replicate your HTTP server, for example, on two physical servers, you can roll it
over easily enough if you have hardware problems.
This is easy to do with servers providing such services as the following: PART V
• HTTP
• FTP
• DNS
• DHCP
• RADIUS
• LDAP
• Active Directory services
These types of servers are easy to switch over if there’s a fault. If one server fails, the other
can step in to pick up the slack.