There
are many reasons to implement a NAS or SAN solution in favor of direct
attached storage. For Exchange Server 2010, if the requirements for
storage consolidation, reduction in mailbox server count, centralized
management of disk resources, service level agreement (SLA)
recoverability times, or near real-time mirroring of data justify the
cost of a SAN or NAS solution, it is time to explore those options. To
make an informed decision about when to make the switch within your
Exchange Server 2010 environment, it is important for you to pass
through several phases:
Analyze—
Gather usage metrics and performance metrics. Determine how storage is
used and how it affects the business processes. Determine if disk
throughput is the bottleneck in your Exchange Server deployment.
Plan—
Determine the current limitations of your storage solutions. Prioritize
the problems and determine if there is a better way. Don’t fall into
the trap of doing things just because they were always done a particular
way.
Develop—
Build the proposed solution for testing. Perform benchmarking to show
improvements over the old methods. Experiment with various functions of
Exchange Server 2010 on different types of disks. Get a feel for the
improvement versus the costs.
Pilot—
Test the solution and improve it based on user feedback. Educate the
user population on how to take full advantage of the new functions and
determine the improvements in efficiencies.
Deploy— Deliver the solution to the masses.
Following this
methodology not only streamlines the process of implementing new and
more-efficient storage technologies, but also provides valuable data to
help upper management buy into the upgrades and support the storage
program for the Exchange Server environment.
Analyzing Your Storage Needs
The first phase of any
good project is an in-depth analysis of the environment and its needs.
For storage systems, it is critical to identify any systems with special
requirements. This includes systems that require multiple layers of
redundancy, systems that are under extremely tight SLAs, and systems
that cannot tolerate a loss of data. For Exchange Server 2010 that is
deployed by role, it is most likely only the Mailbox server role that
can benefit significantly from using SAN or NAS technologies. Similarly,
you might determine that it is less expensive to take advantage of the
additional memory that can be used by Exchange Server 2010 because of
its 64-bit architecture, to increase the caching of database
transactions and, therefore, reduce the necessary number of disks. NAS
and SAN solutions can be expensive compared to purchasing memory for a
server. If the driving force toward a SAN or NAS is performance-based. If your driving force is centralized disk
management, enhanced capacity, or rapid restoration of data, SAN or NAS
might be for you.
Another key
area to understand is the capacity requirements of the enterprise. If an
investment is going to be made in storage, it is a good idea to plan
for several years of growth. Look at the number of servers in the
environment. If additional servers have been added simply because that
is the way things were always done, it is time to look at shifting the
philosophy to doing things because it is the right way to do it.
Tip
Disk drives get
larger, faster, and less expensive each year. When planning for the
future, keep expandability in mind. By buying a partially filled chassis
now and adding additional disks later, you can take advantage of
falling disk prices and save money over the long run and still get the
full capacity needed and the benefits of fewer chassis.
Planning the Storage Solution
Storage technologies
can be confusing. In most situations, valid arguments can be made for
using any of the available technologies. This is a situation in which it
makes a lot of sense to get your vendors involved. Contact your
potential vendors and let them know what your storage requirements are.
Often, they have worked with other companies with similar needs and can
provide valuable insight into what worked and what didn’t. Given the
costs of a large storage system, you can’t afford to do it wrong.
After you have an idea of
what you want to implement, find out if you can contact references to
determine if they were happy with the solution they implemented. Some
companies try to get you to commit to the latest and greatest versions
of their software and firmware. Large storage environments are a big
investment, and business processes depend heavily on it. Ensure that you
implement a stable and well-tested solution.
Tip
A tremendous number
of options are available for storage solutions. When in doubt about a
decision, always refer to the original goals of the project and ask
yourself, “Does this decision support the goals of the project?”
Developing the Storage Solution
After you determine
the needs, explore the options, and devise a plan, the real fun begins.
Any solution that becomes part of the critical path of business must be
developed and tested in a controlled lab environment. This is the part
of the project in which policies and procedures start to take form.
Practice runs of mirroring, failing over of resources, and recovery of
systems ensure that the solution can support the needs of the company.
During this development
phase, practice connecting your servers to the SAN or NAS. Develop and
document standards around HBAs or network interface cards (NICs), the
versions of firmware that will be used, and the version of the drivers
that will be used. Most
SAN and NAS manufacturers provide a detailed list of supported
combinations of hardware, firmware, and software. Deviate from these
approved lists at your own risk. The last thing you want to implement is
an unstable storage environment because you chose not to follow the
recommended configurations.
The development phase
can identify several requirements that are not usually thought of
during the planning phase. Most specifically, these requirements are in
the area of facilities. Most SAN devices are fairly large. An EMC
Symetrix and Connectix, for example, can take up a full rack each. With
heat generation more than 3,000BTUs, HVAC resources need to be
considered. Also keep in mind that most SAN and NAS solutions require
220V to run them. Ensure that planned data center locations have
appropriate space, cooling, and power. Power should include not only the
standard AC feed, but also battery backup. Be aware of any special
requirements of the SAN or NAS. Some SAN devices on the market void
their warranty if they are placed within 5 feet of any solid objects.
Tip
Be sure to carefully
document the entire installation and configuration process. It not only
makes troubleshooting easier, but it also provides the full road map
for pilot implementation.
