Cecil Hypolite wrote, in part:

>I have to do a weekly full backup of a system that has 17 partitions and
>about 500 GB of data. The backup will be done on the weekend, when there are
>few other jobs running. Here are some specs:
>network: 100 MB/sec (12.5 MB/sec)
>SCSI-2 connection : (40 MB/sec)80 MB/sec (two drives)
>Drives: 2 SDLT220's 79.2 GB/hr
>Produce: Netbackup Datacenter 4.5
>
>It seems that the network is a bottle neck as it can only transfer 45 Gb/hr
>(3600 *(12.5 MB/sec) = 45 GB/hr)
>With that network transfer speed of 45 GB/hr I should be able to back this
>500 GB of data within a 12 hour window (11.2 hours to be exact), are my
>calculations correct?
>

The calculations may be correct, but I wouldn't think it wise to plan on 
that throughput.  My best 100mbps clients only get 20-25 MB/hr ... most 
much less.

>-Also since the network transfer speed is only 45 Gb/hr I should not
>implement multiplexing, as one of the drives will start "shoe shining"
>because the network cannot sustain a transfer rate of 79.2 GB.hr. Is this
>correct?
>

I don't understand the reasoning. IMHO, this may be a case where you can 
stand some multiplexing. Already, this client can't give a tape drive 
fast enough.  If you have other data coming in (presumably via another 
network),  the sum of the data would do better at keeping a drive busy.  
Beyond that, if you are restoring, the client's data will still come off 
the drive fast enough to keep the network busy (assuming enough buffers 
and an appropriate level of multiplexing.

Home this helps, wayne