When planning for NAS, location comes first.
NAS - Physical Location
Planning for any form of centralized storage
can be a daunting task, either you are in a position where you have to deploy it
immediately and end up with a tangled mess of files, folders and connections, or
you are in a protracted four-year planning cycle where every potential issue has
an associated taxonomy diagram.
Following are some
NAS planning basics, starting with location.
Make sure you've identified and visited in person where you are going to
physically house the device, make sure the location has adequate power, cooling
and network access and be sure you have the physical room to install an
uninterruptible power supply (UPS) along with your NAS device. Often times some
branch office NAS devices will end up in the maintenance closet, along with high
humidity, dust, poor power supply and a network cable that doubles as a mop
hanger. While not high on most engineers list of to-dos, the lack of power,
cooling and access can turn even the best-planned implementation into an
Power is one of the most basic needs of a
NAS system. If you are not locating your NAS
device in a colocation facility or data center, be sure you pay careful
attention to the power requirements for your device when configured with its
maximum load of disk -- this is key. Your system will grow, and if you plan
ahead for supporting the maximum electrical capacity of your chosen device, you
will save yourself the potential for downtime and costly construction. Planning
for a UPS that can support your NAS for 10 minutes longer than it takes for it
to shutdown is also a good idea. It's important that you plan for brownouts and
surges, and upgrade your UPS when you add shelves to your NAS system.
Be sure you have adequate network bandwidth for
your proposed usage. Flip back to the tip on interconnects for a good rule of
thumb when sizing network bandwidth. If you have a hub-and-spoke style WAN
layout, consider using compression and WAN acceleration devices that will reduce
the impact file traffic will have when coming from your branch offices back to
your central location. Depending on the device you've purchased, you may need
more than one port and IP address. Some NAS devices aggregate multiple network
connections to offer higher performance, so plan contiguous ports on your
network switch for this type of expansion to reduce complexity and to ensure an
easy bandwidth upgrade path.
Planning for storage allocation at the onset
may cause planning paralysis. Do not, under any but the most extreme
circumstances, preallocate all of your disks the instant your NAS arrives,
especially if it is your first implementation of centralized storage. You will
be tempted to carve it up and give all the business units or departments their
share right up front and then forget about it, but this will lead to
under-allocation. Under-allocation with no free disks mean your users will get a
dreaded "out of disk space" error. While you will have the technical ability to
expand the volume you've created, you will have no disk to expand it to. So if
marketing has a big ad blitz going on, you are going to be their least favorite
person. Over-allocation is a little more difficult to deal with because while
expanding volumes is technically possible, most common file systems will not let
you shrink them. So, if you've given 100 GB to accounting and it only uses 4 GB
, you will have to copy that 4 GB off the volume, destroy the volume, recreate a
smaller volume and then copy the data back and reattach it to the server.
Thin provisioning, will help with this problem.