Storage Area Networks For Dummies®

Chapter 6: SANs and Disaster Recovery
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You need to understand the details of each of these questions because each
will affect your plan’s feasibility and required budget. You also need to understand
how recent technical innovations can contribute to reducing the costs
of data recovery — in particular, continuous data protection (CDP), data
de-duplication, sub-block-level storage differencing (data micro-scanning),
and fabric-based continuous data replication (CDR) . (You can find out more
about these topics in Chapter 10 and Part V.) As an example, the budget
required to lease enough network bandwidth to copy 200TB of data is much
greater than the network lease expenses for enough bandwidth to copy only
200GB of data. You should know the going rates for leasing network lines and
which type of network would suit your needs best.
When implementing a disaster-recovery solution, the intersite network connections
used to copy data between sites are usually the most expensive part
of the solution. To be sure of this, just call up your local telephone company
and say that you want to lease a dedicated fibre link between two cities. Make
sure you’re sitting down, though, before you ask for a price.
When sourcing a DR solution for your company, test each vendor’s solution
and the technology they bring to the table to assure you choose the simplest
and most efficient solution available.
Create a detailed plan that
meets your requirements
When drafting your requirements for disaster recovery, these are the details
that need to be considered:
✓ Budget: Determine what you can afford to spend, based on how much
time you can afford to be down. (Refer to Figure 6-1.) As a general rule,
at least 1 percent of gross income is a good place to start.
✓ Remote site: Determine how far away the remote site should be. The farther
the better, to protect against things such as hurricanes and floods.
At a minimum, the site should be on a separate power grid from the production
site. If your company already owns another facility in another
location, determine that location’s feasibility for use as a recovery site.
If that location isn’t practical, you may have to lease floor space from a
hosting facility. (See more on this in the section “Choosing the Recovery
Site,” later in this chapter.)
✓ Replication method: This is how you get your data to the recovery site.
The method depends on your budget, the distance between locations, the
amount of data that needs to be copied, and the number of servers