>> - NET_BUFFER_SZ to 512K or 1M

> Could someone explain when you can and cannot or should and should not 
use 512K/1M.

Veritas explained to me that the NET_BUFFER_SZ is a scratch pad of memory
setup for the transfer of data from the client to the media server. This
value will always negotiate to the lower value between the
client/master/media servers. This does not have anything to do with the
packets of data being sent across the LAN. Think of this being a client
buffer. In the event of a SAN Media Server a touch file of
<install_path>/NetBackup/NOSHM allows the SAN Media Server to use this
NET_BUFFER_SZ memory area and setting a value of 512K/1M will in some cases
improve performance. Increasing this value should not cause any problems. In
the case of a SUN Server the /etc/system values for shared memory may have
to be increased.

By default the NET_BUFFER_SZ is 32K. This is a very small buffer for
information to be transferred over the 100MB/FullDplx or Gig-E LAN. I have
used this "little trick" for performance tuning of SAN Media Servers and it
has not yet let me down ;-)

The largest tape buffer size supported by Windows 2000 is 64K, again this is
a painfully small value for a modern SAN attached tape device. The
NET_BUFFER_SZ will give NetBackup more memory for buffering writes to tape.

Just my unreliable 2 cents...

Please contact me on list if my information is wrong or misleading.