On Wed, 5 May 2004, Robert McCarthy wrote:

>One thing I noticed with Gb NIC's is the bus speed of the system matters
>ALOT.. and is it a 64 bit PCI slot or is it a 32 bit slot.  The few Gb NIC
>I have had disclaimers about limited bandwidth using 32 bit slots.  And
>make sure you check your drivers!

Another thing I discovered with Sun hardware is to try to spread the
backup load across as many PCI channels as the server has. For example,
my NetWorker server is a Sun Enterprise 450 and we have it set up so
that two of our NDMP devices sit on one PCI channel and the other two
sit on the system's second PCI channel. This maximizes throughput.
We have a total of twelve tape drives in our library; all connected
via SCSI and we were careful to balance the SCSI connections across the
PCI channels as much as possible.

The only way to do this is to study the schematics for the machine.

Also, a good way to test network connectivity speed is to take a one GB
file and ftp the file from each client to the NetWorker server and note
the transfer times. One source of the bottleneck might be the client(s).

The other thing to test is to use the Unix cp command to copy the same
file directly to each tape drive as in

time cp test_file /dev/rmt/0cbn

and see what the output of time is. Of course, do this only on scratch
tapes.

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