Yesterday, today and tomorrow
When disaster waves, I try not to wave back
Mason Cooley, U.S. aphorist
was 20 years ago today when Fortune Magazine noted that off-site computer data
storage was booming. Even then the concept of DR as evinced by storing tape
backups in a location far, far away from your primary location wasnt new,
the magazine noted that this kind of service had been around from the early
1950s. So you see, DR isnt new, it started long ago.
For a business, a disaster is the end of the world as far as it is concerned.
An inadequate DR infrastructure can lead to shutters slamming down and RIP being
carved on a business gravestone before you can say 3DR, CDP or any of
the acronyms that the study of DR compels one to get familiar with. Some of
these technologies help a business on an everyday basis, not only when disaster
strikes. For instance, using disk instead of tape for first-level backups can
slash the backup window and improve productivity by bringing a production system
online in minutes instead of hours. This could be done by using virtual tape
libraries that emulate a tape library while writing data to inexpensive SATA
disks. Which is not to say that tapes outmoded. Far from it, its
now the final frontier, the last line in the DR front. Hence the need for 3DR
where a SAN array writes data to a nearline or VTL box, which is backed up to
another disk box in a remote location and from there its away to tape
for the worst case scenario backup.
CDP or continuous data protection in tandem with WAFS or wide-area file services
can be an unbeatable albeit expensive answer to instant recovery. These solutions
mirror and synchronise data across locations over a WAN and keep your business
systems accessible even if your primary site takes a hit. To keep the amount
of data flowing down those WAN links at a reasonable level, companies can use
techniques such as data segregation (decide whats important and whats
not; e.g. your ERP database is critical, presentations are probably not), deduplication
(backup only one copy of a large e-mail that went out to the whole marketing
department) and delta differential synch transfers (only send those blocks or
files that have changed since the last backup). Then theres the question
of equipment. Traditionally youd need your secondary site to mirror the
configuration of your primary. Thanks to virtualisation thats no longer
So where is DR technology headed? Some trends are clear.
Replication speeds are on the rise, costs are waning and its just a matter
of time before grid technology gets co-opted for DR in many-to-many topologies.
Virtualisation is having a profound impact on every sphere of IT be it servers,
desktops or storage and DR is no exception to that rule. Tomorrow, DR will be
a given. Smaller organisations will most probably outsource it to third-party
data centres and larger ones will give it no more thought than any other fundamental
part of their IT architecture.
Prashant L Rao
Head of Editorial Operations