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up data for the purpose of taking it
somewhere else for use. These three reasons
need to be addressed in your backup
strategy.
Tape backups have become the technology of
choice for backing up computer data. This is
due in large part for its ability to store
large amounts of data, in a relatively short
amount of time. Its popularity has helped
keep pricing affordable, and its ability to
use removable tapes allow for flexible
implementation of various backup strategies.
The ability to remove the backup tape and
use a new backup tape is an important
concept for the following strategies.
The basic premise of a tape backup strategy
for disaster recovery uses two different
tapes. One tape is designated as the current
backup tape. This is the tape that has the
most current data on it. If storage space
permits, you may be able to store several
days backups on one tape, or you may simply
keep replacing yesterday’s backup with
today’s, or you may even use multiple
“current” backup tapes (more on this later).
Now that you have your current data backed
up, you need to prepare for disaster. If
your office catches on fire, your backup
would be lost, too! To prevent this and
other catastrophe scenarios, we use a second
tape for off-site backups. At least once a
week you should take your current tape to a
safe, remote location such as home or a safe
deposit box and replace it with the your
previous off-site tape. The tapes have now
switched places ensuring that you have a
current tape, and a fairly current tape
off-site for disaster recovery. We have thus
properly implemented a strategy that covers
the first purpose of tape backups, disaster
recovery.
Now we must make a modification to our
current tape backup strategy to address
integrity recovery. Integrity recovery
involves using several “current” tapes. I
recommend a minimum of five days of backup
tapes for your current set and one tape for
off-site backup. You can rotate your
off-site tape every week or day as time
permits. Now you still have your disaster
recovery plan in place, but you also have
the capability of going back through several
days of backups if a file is accidentally
deleted. To illustrate, let’s say I
accidentally deleted the payroll spreadsheet
on Tuesday. When payroll is run on Friday,
the problem is discovered. If we were using
a tape backup
solely for the purpose of disaster recovery,
we would only be able to restore a file that
is a week old, since the backup would have
replaced Tuesday’s data with the most
current data that did not contain the file.
With our new integrity recovery backup
strategy, we can go back to Tuesday’s data
to retrieve this file. By adding even more
tapes to this scheme, we can extend this
one-week window for integrity recovery to
two-week, months and even more. By simply
adding more tapes and modifying our tape
backup strategy, we can maintain current
data for use in integrity recovery.
Are tape backups all good? Not quite. When
it comes to data transport tape backups fall
a bit short. The good news is, there are
other options for data transport that are
readably available and cost next to nothing
to implement along side a good tape backup
strategy. These options include internet
transfers, floppy disks, zip disks, and
dozens more. Data transfer should be the
topic for another article. Just keep in mind
that data transfer is a purpose of data
backup but not specifically tape backups.
In conclusion, there are only good reasons
to have a tape backup strategy. We must be
conscious that the purchase of a tape backup
system is not enough; it also requires a
good tape backup strategy that takes into
account disaster recovery and integrity
recovery. Tape backup technology and
planning are very different from business to
business, so you should always consult with
your computer professional when researching
a change in your data backup strategy.
--
Allen D. Edwards holds a BS in Computer
Science and is President of HiQ Networking,
Inc., which can be reached at (912)
756-6767.
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