From $300 filer appliances to gateways fronting data
network-attached storage (NAS) covers an enormous amount of territory. To
get the most out of your NAS device, you need to consider your needs and options
carefully. Here's a list of six questions smaller businesses can ask themselves
to help determine whether or not they should invest in a
NAS system, and what to look for in a NAS system.
How much data storage
do you need now?
This is the basic question you need to answer when adding NAS to your data
storage environment. How much storage do you have now? Are you trying to replace
all the data storage on your system with NAS storage, supplement what you have,
or provide storage for a particular application? Answering these questions will
give you a basic foundation for understanding your NAS needs.
How much storage will you need in 18 to 24 months?
From a one terabyte appliance to a gateway backed by a petabyte or more of
storage, NAS comes in all sizes -- at a price. The trick is to estimate how much
storage you'll need in the forseeable future and get a NAS system that can
handle that much data growth.
It's easy to get into a pattern of meeting immediate storage needs by adding
another NAS device. However, that can result in management headaches as you try
to handle a bunch of separate devices. It can also lead to inefficient use of
storage resources because your total NAS capacity is scattered among different
It is better to estimate your storage growth and purchase a system which can
be expanded to keep pace with that growth. Start by looking at your logs to see
how fast your storage needs have grown over the last year or so. Project that
out and add a cushion -- usually 20% -- to arrive at your estimated growth.
Most of the time, your best bet is to purchase a NAS device which is
expandable, either by adding higher capacity disks to an appliance or by adding
more disk arrays. All of the major NAS suppliers offer expandable NAS devices
such as the
from Overland Storage, which allows for up to 7
S50 JBOD Expansion Units.
Do you have the bandwidth on your LAN?
By its nature, NAS puts an additional load on your
local area network (LAN) as files are shipped back and forth between the NAS
device and the users. If your network is already near capacity, the performance
of even the fastest NAS device will be disappointing.
How much bandwidth you need depends on the current load on the network and
the load the NAS will add. The added load in turn depends on the way you will
use NAS. Generally speaking, it is easier for NAS to handle many little to
medium-sized files than a few large ones. Shipping big graphics files around
with fast response times takes more network capacity than moving small- to
medium-sized files over the network.
A good way to determine whether or not you have enough bandwidth is to look
at your LAN's log files. Check to see how heavily loaded your existing LAN is
and then extrapolate based on the size and number of files you'll be adding to
the network load with NAS.
Except in small installations, you generally want at least a
Gigabit Ethernet network or the equivalent. Similarly, if you use routers or
gateways, keep the NAS device topologically close to the users.
How well will network-attached storage integrate with your data storage
Just about anything that calls itself
data storage management software will support at least some NAS devices.
However, few of these applications will support all
NAS devices on the
market. You need to make sure that your storage management software -- whether
existing or newly purchased -- will support all your storage. At a minimum, your
SMS should be able to discover NAS on the network, configure it and provide a
reasonable level of security for all your users.
Also, checking compatibility involves working with both the NAS and software
vendors to make sure the combination will do what you want it to do.
Is the NAS device clusterable?
Clustering involves attaching NAS devices so they can work together. This
improves performance by spreading the workload over more than one set of
processors in the NAS devices. Clustering also offers better expandability, load
balancing and increases the bandwidth between the NAS devices and the network.
Not all NAS devices are clusterable, although most of the midrange and nearly
all the high-end NAS devices are clusterable. If your expansion plans call for
significant increase in NAS capacity, i.e., doubling NAS storage or more,
clustering is worth investigating both for the added reliability of redundancy
and improved day-to-day performance.
Does the NAS device do scheduled backups?
A NAS device is a critical part of your data storage architecture and should
have the ability to do automatic data backups on a schedule. The devices with
this capability can typically be backed up either to an external disk connected
to the NAS device via a USB port, or over the network to another disk or disk
array. This feature is found on most NAS devices except the very smallest.
Typically the NAS comes with a utility that will allow you to set up the backup
schedule and will also take care of doing the backups. You may also want to
schedule your backups through your data storage management software.
Buying NAS storage isn't especially complicated. It is mostly a matter of
thinking about what you need now and what you will need in the future. Generally
how much data storage you are adding will determine how much time and effort you
will want to put into choosing a NAS device.