Network Attached Storage (NAS) & Storage Area Networking (SAN)
As businesses grow the demands for network storage increase,
they follow a natural progression of storage environments. As direct-attach storage (DASD) on
their Windows servers becomes insufficient, businesses frequently move on to network attached
storage (NAS) or storage area networking (SAN).
The full promise of storage not directly attached to the server is best fulfilled by implementing
a SAN, which has advantages in performance, reliability, availability, and provisioning.
But the overwhelming benefit of SAN storage often gives storage administrators the
false impression that by simply implementing a SAN and following the vendor’s instructions,
they will achieve the best possible performance and reliability in their Windows Server-based network.
Read more on SAN performance »
How do I get the most performance from my SAN?
At some point a SAN administrator will realize that the SAN storage is no longer performing
as well as it once did. Investigating the cause of the performance slowdown
usually indicates problems with free space or available storage.
The administrator may wonder what is causing all the unexpected I/O,
and increasing the amount of storage available is usually the
easiest solution. However, in many cases adding storage is unnecessary because
storage on the SAN is not the problem.
One of the most significant issues, and the most unrecognized,
is fragmentation in a SAN storage system. With the implementation of a SAN, many Windows Server administrators
believe that fragmentation, which they accepted and dealt with when using DASD storage, has gone away.
This belief, the storage administrator frequently fails to consider file fragmentation
when evaluating the problem of reduced SAN efficiency. When SAN performance problems
are noticed, the knee jerk reaction is to add additional storage, with the presumption
that the lack of free space is causing the SAN to slow down. However, both overall
performance and storage efficiency can be affected by file fragmentation that occurs
when Windows Server writes data out to storage, regardless of whether that storage
is DASD, NAS, or SAN.
Effects of File Fragmentation on SAN storage
The effects of file fragmentation in SAN storage often manifest in reduced application performance and
inefficient use of storage. Application response times begin to degrade, the time necessary to load
large files and applications grows longer, and the overall user experience is negatively impacted.
End-users begin to feel that their computer is slowing down, leading to help desk calls with complaints
about network performance or some other imagined problem. The reality is that file fragmentation is
simply causing data manipulation times to increase to the point where the delay becomes perceptible
to the end-user.
Diskeeper® I/O performance software offers technologies
designed to help companies make their SANs run more efficiently and boost the performance of their applications.
While traditional methods of handling fragmentation may cause some extra write activity or thin-provisioning
growth in SANs, Diskeeper’s preventative fragmentation technology – IntelliWrite, is fully compatible
and extremely beneficial for SANs. With CogniSAN™ technology, Diskeeper 12 Server detects external resource
usage within a SAN allowing for increased performance without intruding in any way into SAN – layer
VM accelerator does the same with VMs.
Download a free copy of Diskeeper or V-locity server to test on your SAN