3. Location, Location, Location
One factor tends to consistently blur the line
between regular backups, disaster recovery, business continuity, and
even high availability: where your solution is located. We have talked
to many administrators who have the false assumption that once a
recovery activity moves off-site, that automatically makes it disaster
recovery (or business continuity, or high availability). This is an
understandable misconception — but it's still not true.
In reality, the question of "where" is immaterial.
If you're taking steps to protect your data, it's backup and recovery.
If you're taking steps to rebuild services, it's disaster recovery. If
you're taking steps to ensure you can still do business, it's business
continuity. This is obviously an oversimplification, but it'll do for
now unless we start looking at all the ways the lines can blur. We do
want to touch on one of those complications now, however: where you
deploy your recovery operations. There are three overall approaches:
on-premise, off-premise, or a combination of the two.
3.1. On-Premise Solutions
Most of what we do as Exchange administrators, especially in the backup and restore problem space, is on-premise.
In an on-premise solution, you have one or more sites where your
Exchange servers are deployed, and those same sites host the backup and
disaster recovery operations. Note that this definition of "on-premise"
differs somewhat from traditional disaster recovery terminology, which
talks about dedicated disaster recovery sites. These sites are still part of your premises and so are still "on-premise" for our purpose.
Many organizations can handle all their operations
in this fashion through the use of Exchange, storage and networking
devices, and third-party applications. Some, however, can use
additional help. When you need on-premise help in the Exchange world,
there are two broad categories:
Appliances
Appliances are self-contained boxes or servers,
usually a sealed combination of hardware and software, placed into the
network. They are designed to interface with or become part of the
Exchange organization and provide additional abilities. Appliances are
useful for smaller organizations that want sophisticated options for
disaster recovery but don't have the budget or skill level to provide
their own. Appliances can be used to provide services such as
cross-site data replication, site monitoring, or even additional
services aimed at other types of functionality.
On the plus side, appliances are typically easy to
install. On the downside, they can quickly become a single point of
failure. The temptation to place an appliance and treat it as a
"fire-and-forget" solution is high. In reality, most appliances need to
be tested, monitored, and upgraded on a regular basis.
Remote Managed Services
Remote managed services (or remote management)
are service offerings. Instead of buying a sealed black box, the
customer purchases a period of service from a vendor. The service
provider provides design, deployment, and ongoing maintenance services
as part of the offering for the customer — sometimes as a package,
sometimes as a set of a la carte offerings. Like appliances, these
offerings can extend beyond traditional disaster recovery offerings.
These types of service providers are able to provide
trained Exchange expertise on a scale that is typically only available
to very large organizations. They can do this through economies of
scale; by using these highly trained personnel to monitor, maintain,
and troubleshoot many disparate customer organizations of all sizes and
types, they can both afford this type of staff and offer them the kind
of challenges necessary to retain them.
Some solutions exist that combine these two
approaches; customers purchase both an appliance as well as a managed
service offering.
3.2. Off-Premise Solutions
Some problems are easier to solve — or more
efficient to solve — if you let someone else deal with them. In the
Exchange world, this translates to hosted services
— services or offerings provided by a third party. Hosted services
provide a large variety of functionality to an Exchange organization,
ranging from backup, disaster recovery, and business continuity to such
services as message hygiene, archival, and compliance and governance.
There's a close similarity between hosted services
and remote managed services. Both are provided by an external service
model. They can both offer a combination of features, performance, and
convenience that makes them attractive to small and medium-sized
organizations. The difference is that with hosted services, messaging
traffic is diverted — whether externally or internally — to the hosting
provider, which then performs specific actions. Depending on the
specific service, traffic can then be rerouted back to the organization.
Most hosted services charge on a per-user or
per-mailbox basis, which is part of the reason why they tend to be
favored by smaller organizations, or for specific portions of a larger
enterprise. They can also require a large amount of bandwidth,
depending on the overall amount of messaging traffic your organization
is sending to the service. This can drive the costs higher than just
the up-front per-mailbox price.
One of the main differences between hosted services
and remote managed services is that a hosted service provider commonly
(but not always) has an internal Exchange deployment that is designed
to host multiple tenants. For many years, the retail version of
Exchange Server has assumed that each deployment will be used for a
single organization or corporate entity. In fact, legacy versions of
Exchange have been difficult to manage in the cases where one
organization splits into two, or multiple organizations are merged or
joined into one. However, there have been hosted versions of Exchange
that were made available to specific Microsoft partners, allowing them
to create and host multitenant Exchange deployments.
With Exchange 2010, Microsoft specifically worked on
implementing their own hosted solution to gain operational experience
with multitenant architectures and fix Exchange design features that
caused problems with those architectures. As a result of this work,
Exchange Server 2010 now explicitly recognizes off-premise hosted
services that are based on the Exchange 2010 platform. As a result, the
Exchange 2010 management tools are designed to work both on on-premise
deployments as well as those hosted services. As more service providers
move to support Exchange 2010, be sure to investigate their integration
with the native Exchange 2010 tools.
