IBM Systems Magazine, Mainframe - January/February 2018 - 34
BC Tier 1: Restore from offline
media, most often tape
Typically, backup tapes are
created and periodically shipped
to an offsite storage facility.
Depending on how often this
happens, the organization must
be prepared to accept several days
to weeks of data loss. Recovery
will require someone to pick up
these tapes and take them to the
BC Tier 2: Tapes in a hot site
Similar to Tier 1, but with the
offline media shipped to the designated recovery location. A "hot
site" implies servers, storage and
network equipment are already
in place to perform recovery from
these backup tapes.
BC Tier 3: Electronic vaulting
Rather than shipping physical media, data is transmitted
electronically and stored on tapes
or other media at the recovery
location. This eliminates many of
the problems associated with boxing up backup tapes, providing
them to couriers and having them
received at the recovery site.
BC Tier 4: Point-in-time copies
Flash and disk storage data can
be copied at specific points in
time (e.g., every four hours) and
electronically sent to the recovery
facility. When a disaster occurs,
the point-in-time copies may
need to be cleaned up for partial
or incomplete transactions that
were in play at the time the copies were made.
BC Tier 5: Application/database
For some business processes,
transactional integrity is critical.
By integrating with specific application or database capabilities,
BC Tier 5 provides for little or no
data loss. This can be accom-
Figure 1: Disaster Recovery Levels
plished by sending transactions to
secondary copies of the databases
at the recovery locations. This is
sometimes called log shipping
or database shadowing. Unfortunately, this only addresses the
subset of data and applications
that support this, leaving all
unstructured data to be recovered
some other way.
BC Tier 6: Real-time continuous
Often referred to as mirroring,
BC Tier 6 eliminates dependencies on application or database
capabilities and covers all data,
both structured and unstructured.
Synchronous replication means
that the data at the recovery
location is identical to the data at
the primary location, RPO of zero.
Asynchronous means the data at
the recovery location may be a few
seconds or minutes behind.
BC Tier 7: End-to-end resiliency
Tier 6 only addresses the data on
storage devices. BC Tier 7 adds
complete orchestration to address
the server and network components
of the infrastructure as well. Servers
are booted up, applications are
started and networks are redirected
to match the new location.
34 // JANUARY/FEBRUARY 2018 ibmsystemsmag.com
All of these tiers are available
today with existing technologies.
Organizations that have BC Tier 7
implemented have the ability to
recover from a site wide disaster
in less than 30 minutes.
Keep Testing Current
don't have a
All of the people involved in the
preparation and recovery of information should understand their
roles and responsibilities. Management should ensure all procedures
are documented, and employees
are trained to handle a disaster.
Consider testing your BC/DR plan
at least once a year. Some companies test more frequently. Some
testing can be done on-premises, at
the designated recovery site or at a
third location. Even a walk-through,
where all parties get together in a
conference room and talk through
what steps they would take, is a
DR is a business solution, not
just technology. While this article
focused on the effect of losing IT
technology and facilities, your
BC/DR plan should also consider
other effects, workforce shortages
and supply chain disruption.
Tony Pearson is a Master Inventor
and senior IT architect with IBM