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http://www.oracle.com/technology/oramag/oracle/07-mar/o27field.html
COMMENT: In The
Field
New
Strategies Simplify Backups
By
Innovative technologies speed up tasks and reduce
costs.
Backing up data used to be simple. At night, when
system use was low, you physically copied everything to tape. If you needed
more space, you bought more. Backups might take several hours, but that didn't
bother most people. If you ever had to restore the data, you just copied
everything back into place. Life was good.
Now things aren't so simple. Data size and the costs to
store backups have grown by double digits—but your enterprise's income
and profits probably haven't. That once-small backup window threatens to dwarf
the active production window, especially since your enterprise now handles
transactions 24/7. If a disaster requires restoring all that data, it had
better be done yesterday.
Now new backup technologies are making it possible to
back up data more completely and economically, using less space, with simpler
and faster restore procedures and intriguing side benefits. These backup
technologies don't require faster drives, although better hardware helps.
Instead, these technologies involve better ways of handling the data you want
to back up. Best of all, they also work well in Oracle environments.
How good are the new backup solutions? In the past,
recovering one terabyte of backed-up data might take up to 15 hours and require
considerable manual handling of tapes. Now, recovering that same amount of data
requires only minutes and is largely automated. Take Oracle Recovery Manager
(Oracle RMAN). Before Oracle RMAN was introduced, backup required physically
copying each database-related file, writing every byte. Oracle RMAN is far more clever. Instead of writing every byte, Oracle RMAN
backs up only blocks of data that have changed, resulting in backup sets that
are a fraction of the size of the original database, require fewer disks or
tapes, and are faster to restore.
Snapshots are another approach to backups. This system
of pointers saves the original backup information in one area and points to new
blocks when data is changed. If recovery is necessary, you just select which
set of pointers to use as production, resulting in a near-immediate recovery.
Since the snapshot consists of pointers, it can require far less space than a
full backup, and because you are handling pointers to data rather than data
itself, you can restore terabytes of data in seconds rather than hours.
Creating a snapshot is also fast compared to physically
copying data, with essentially no performance hit to the production system. As
a result, you can do more-frequent (and more-granular) full backups of your
data, which reduces the risk of not being able to recover completely. Imagine
how much simpler and quicker it is to restore from hourly full backups instead
of nightly incrementals with weekly full backups.
Using snapshots offers another bonus to shops that
create test and development systems. In the past, you had to duplicate a
production database on a separate system to test new development. This took a
long time and required a lot of hardware. As a result, many development teams
cut corners and did inadequate testing with incomplete data.
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However, snapshots let you use the same pointers to backup
data in your test systems without moving the actual data, so you can set up
test systems in minutes rather than days, on a system that is more compact and
economical. As a result, cloning full production data to test and development
systems is far easier. Indeed, removing this bottleneck permits multiple test
environments simultaneously, reducing time to deploy applications and freeing
up database management and resources.
Deduplication is another approach to backups. This technology looks for duplication
in data that is headed for backup and records only one copy of similar data.
Suppose an e-mail arrives in your inbox (which requires a backup), and you
forward it to colleagues (which also requires a backup). Come backup time, deduplication solutions will recognize the similar data,
save only one copy, and use pointers to that one copy for any similar material.
The upshot: far less space is required for backups. The process is invisible to
both the user and the application—all they see is faster backups and less
tape to manage.
How much can you save by changing your backup habits?
Using this combination of technologies, the amount of data being moved for
backup can be reduced by more than 90 percent.
Oracle's backup solutions, including Oracle RMAN and
Oracle Data Guard, incorporate some of these strategies. Smart use of these
solutions can simplify backup and restore tasks, save costs, and improve
performance. Life is better.
