Fragmentation on sql server

SQL2K Ent SP3a Win 2k Adv
We've SAN disks showing high levels of fragmentation and have been
looking into defragmenting this disks with a 3rd party tool, as Win2K
won't defrag anything with block sizes > 4k.
Reading:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/sql/maintain/optimize/ss2kidbp.asp
states;
"On large-scale environments that benefit from more intelligent disk
subsystems, such as SAN (storage area networks)
environments, correcting disk fragmentation is not necessary."
Can anybody explain (or indeed refer me to some information on this), for my
benefit and others, why this is the case? Even with a
large cache, to my mind, fragmentation must have some performance hit.
All ideas welcome.That is because the disk management tools on NT or on any
SAN client are designed for direct physical access (i.e.
they work on local drives), and currently they treat SAN
drives also as local drives. But they really don't know
about the actualy disk layout on SAN, even today's SAN
tools cannot give you much information. it is all
guesswork by SAN admins.
This is tauted as one of the advantages of the SAN that
physical disk management is transparent to the OS and you
can change your disks layouts without affecting OSes. but
because of this you can't use existing tools to monitor
and manage SAN drives from the client tools. SAN is a new
technogogy and it has yet to develop such tools to work on
SAN. I don't know of any SAN vendor who supplies any good
tool for disk monitoring and management. First or second
generation of such tools will not run on NT but you have
to use terminal client interface for it. And may be well
after a while in future they will come up with a nice gui
and accurate tool that can run on NT.
>--Original Message--
>SQL2K Ent SP3a Win 2k Adv
>We've SAN disks showing high levels of fragmentation and
have been
>looking into defragmenting this disks with a 3rd party
tool, as Win2K
>won't defrag anything with block sizes > 4k.
>Reading:
>http://www.microsoft.com/technet/treeview/default.asp?
url=/technet/prodtechnol/sql/maintain/optimize/ss2kidbp.asp
>states;
>"On large-scale environments that benefit from more
intelligent disk
>subsystems, such as SAN (storage area networks)
>environments, correcting disk fragmentation is not
necessary."
>Can anybody explain (or indeed refer me to some
information on this), for my
>benefit and others, why this is the case? Even with a
>large cache, to my mind, fragmentation must have some
performance hit.
>All ideas welcome.
>
>.
>