Every now and then, I like to take time and concentrate on
tape backup and its role in Disaster Recovery (DR). While so much attention is
placed on disk backup, real-time and snapshot replication, and other more
modern technologies, tape backup allows for both a good basic plan and a vital
addition to a more well-rounded enterprise-class DR
solution. My point is that you shouldn’t put all your eggs in one basket when
it comes to protecting your data. These backup methods have advantages and
disadvantages
that you should take into account when creating your recovery
plan. Relying
on any single method
could put you at risk, while mixing elements of
available technologies adds to your security.

As a methodology for DR in itself, tape allows you to take a
copy of your data and move it to another location besides the server it’s
currently sitting on. This means that on a regular schedule—once per day, for
example—you would commit all data or just the changed files to a removable tape
cartridge. At that point, the tapes should be removed to another location for
safe-keeping, as anything that hits the server room (fire, flood, etc.) could
endanger any on-site tapes as well.

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From this basic idea, you can begin to craft even more complex
solutions using just tape backup. Many organizations perform daily backups, full
weekly backups, and sometimes even monthly backups. Some tapes are kept on-site
for immediate restoration in the event of need, while others are rotated
off-site for safety. Organizations can tape once per day, take snapshots with
different tools, and commit the snapshots to tape on a regular basis throughout
the day, etc. This venerable technology still has a place as basic DR in its
own right.

Once
your organization grows beyond the ability of tape to provide full DR, you will
still want to use tape technology as part of your overall DR plan. Replication
systems leave you open to the possibility that corrupted data on one server
could easily be replicated to other servers before you detect the malicious
intent of an intruder. Snapshots and other point-in-time copies are still
housed on moving disks—great for quick recovery in some situations, but ultimately
undependable in a full-blown disaster. Since the disk must reside in a server
for the snapshots to take place, you cannot effectively use a snapshot system
to natively get data away from production machines. While you could replicate
the data to another site, that data would still fall prey to malicious intent
and/or virus activities, which both could easily destroy data on the production
and replicated servers alike. Adding tape into the equation allows you to
easily remove point-in-time copies from volatile locations and house them
securely at a remote site for true DR.

Tape copies that have been securely warehoused off-site can
help you recover from disasters that these other methodologies do not
adequately protect against, and are therefore still a vital part of your
solution.

No matter what size organization you are part of, or how
intricate your DR plan is, you will still want to make tape backups a part of
your overall plan. Even if you hope you never have to use them, they will more
often than not save your data when—literally—all else fails.