What you are talking about is called "mirroring" and the normal way to
accomplish it is with RAID 1. Read about RAID here:
http://en.wikipedia.org/wiki/RAID
RAID 1 (mirroring) is *not* a backup solution. RAID 1 uses two or more
drives, each a duplicate of the others, to provide redundancy, not backup.
It's used in situations (almost always within corporations, not in homes)
where any downtown can't be tolerated,
because the way it works is that if one drive fails the other takes over
seamlessly. Although some people thing of RAID 1 as a backup technique,
that is *not* what it is, since it's subject to simultaneous loss of the
original and the mirror to many of the most common dangers threatening
your data--severe power glitches, nearby lightning strikes, virus attacks,
theft of the computer, etc. Most companies that use RAID 1 also have a
strong external backup plan in place.
Here's my standard advice on backing up:
First of all, almost everyone should be backing up regularly. It is always
possible that a hard drive crash, user error, nearby lightning strike,
virus attack, even theft of the computer, can cause the loss of everything
on your drive. As has often been said, it's not a matter
of whether you will have such a problem, but when.
Essentially you should back up what you can't afford to lose--what you
can't readily recreate. What that is depends on how you use your computer
and what you use it for.
It takes time and effort to backup, but it also takes time and effort to
recreate lost data. If you back up daily, you should never have to
recreate more than one day's worth of last data. If weekly, there's
potentially a lot more to recreate. You should assess how much pain
and trouble you would have if you lost x days of data, and then choose a
backup frequency that doesn't involve more pain and trouble than that you
would have if you had to recreate what was lost.
Some things (photographs, for instance) can never be recreated, and more
frequent backup may be wanted for them.
At one extreme is the professional user who would likely go out of
business if his data was lost. He probably needs to back up at least
daily. At the other extreme is the kid who doesn't use his computer except
to play games. He probably needs no backup at all, since worst case he can
easily reinstall his games.
Most of us fall somewhere between those extremes, but nobody can tell you
where you fall; you need to determine that for yourself.
Should you back up Windows? Should you back up your applications? Most
people will tell you no, since you can always reinstall these easily from
the original media. But I don't think the answer is so clear-cut. Many
people have substantial time and effort invested in customizing Windows
and configuring their apps to work the way they want to.
Putting all of that back the way it was can be a difficult, time-consuming
effort. Whether you should backup up Windows and apps depends, once again,
on you.
How to backup? What software to use? There are many choices, including the
Windows-supplied backup program. Which choice is best for you depends at
least in part on the answers to some of the questions above.
Finally what backup media should you choose, and how should it be stored?
There are many choices, including CDs, tape, zip drives, and second hard
drives.
I don't recommend backup to a second non-removable hard drive because it
leaves you susceptible to simultaneous loss of the original and backup to
many of the most common dangers: severe power glitches, nearby lightning
strikes, virus attacks, even theft of the computer.
In my view, secure backup needs to be on removable media, and not kept in
the computer. For really secure backup (needed, for example, if the life
of your business depends on your data) you should have multiple
generations of backup, and at least one of those generations should be
stored off-site.
My computer isn't used for business, but my personal backup scheme uses
two identical removable hard drives,I alternate between the two, and use
Acronis True Image to make a complete copy of the primary drive.
I also use a pair of 1GB thumb drives for making more frequent backups of
my most critical data (like financial information). For that I just drag
and drop.
