Storage consolidation is the practice of
simplifying the storage infrastructure, allowing storage
administrators to increase organization and control over their
resources. The need for storage consolidation stems from one
indisputable fact: Storage needs keep growing. In fact, most
organizations struggle just to keep up with the insatiable
storage demands of users and applications by continually adding
disks, arrays and servers.
Over time, these organizations eventually suffer the effect of
storage sprawl, where data is stored on disks and systems in the
data center, throughout the organization and even across the world
by virtue of remote offices and mobile users. This proliferation of
storage assets presents three main problems: the expense of new
storage, an increase in storage management overhead and a strain on
facilities (e.g., power and cooling). As a consequence, storage
consolidation has become a priority for many data centers.
Any storage consolidation initiative should start with an
evaluation of the advantages and disadvantages. Most storage
consolidation efforts involve replacing multiple disparate storage
platforms with a single storage resource. For example, an
organization with 400 storage servers spread out over the
enterprise could consolidate its storage into a single storage area
network (SAN) or a network attached storage (NAS) system, one
typically located in the data center.
Storage consolidation: The upside
Storage consolidation holds out the promise of management
efficiency. There are fewer storage platforms to manage.
Administrators don't need to track and maintain a multitude of
servers. Heterogeneous management software often allows
administrators to organize and provision consolidated storage
through a single control panel.
The net result is less time spent managing with fewer errors.
With fewer systems to manage, there's no need to hunt for free disk
space on long-forgotten servers, so administrators can use the
available storage to a much higher percentage. For example, the
storage on distributed servers rarely sees more then 50%
utilization; consolidated storage utilization can easily exceed
80%. Recovering this forgotten storage can result in significant
cost savings.
These simplifications also make it easier to "see" the storage
in order to generate utilization reports and even predict future
storage needs. Such storage resource management (SRM) in turn
allows organizations to save money by budgeting storage
acquisitions more accurately. It also helps them take advantage of
falling storage costs over time -- a tactic that analysts suggest
is more cost-efficient than making bulk disk purchases today.
Finally, reducing the number of storage systems often minimizes
power and cooling demands on data center facilities.
Storage consolidation: The pitfalls
Storage consolidation also has downsides, such as network
performance. With storage concentrated in a few centrally located
devices, all of the storage traffic will pass across the same
network connections. This can lead to a serious performance
bottleneck, which can impact application performance and user
service levels. Therefore, it's important to evaluate the network
architecture early in the storage consolidation process and
accommodate any changes or upgrades needed to ease potential
bottlenecks.
With more users relying on fewer storage systems, experts also
point to potential reliability issues and recommend the use of
high-availability architectures, such as trunking and failover, to
ensure that storage remains accessible in the face of network or
storage system problems.
Storage consolidation can also further complicate data storage
management. The most immediate problem during a consolidation is
data migration, since the data from a myriad of disparate systems
must be moved to the new storage system(s). In many cases,
migration must occur with little (if any) actual downtime for
applications. Bottom line: Be sure that new storage systems offer
adequate data migration tools.
Post-deployment, you'll need to address data backup and disaster
recovery processes. Backup windows may increase dramatically when
backing up a large concentration of data, and this may require
disk-based backup techniques such as virtual tape libraries or
disk-to-disk. Some users who consolidate to a single large NAS will
replicate to a duplicate NAS in another physical location.