>      - Yes, we really are only getting 1.5 - 2 GB/hr on the OSA
>      - Our network configuration for inbound traffic is through an ATM
>        router, to the ATM switch, the ATM cloud (155 MB/s), and to the OSA.
>        Again, ALL inbound traffic comes through this route.  I'm not really
>        a network guru, so I can't get much more specific than that.
>      - We are running OS/390 2.4, TCP/IP 3.2 (not the rewritten version)
>        soon to be 3.4 (June), which I understand should help the situation.
>        We do have a socket reserved for ADSM use only.

We have a network configuration similar to this. We are still in the test
phase, and it is a bit difficult to compare our measurements to complete
backups of production systems. As best I can estimate, we are getting
somewhere between 50% and 100% better throughput than quoted above. The most
useful thing we have done so far in terms of tuning is increasing the packet
size. We started off using 576 byte packets (the default for connections that
go through a router). Our network experts changed the configuration of MVS
TCP/IP to make it use 1024 byte packets in this case. Throughput went up by
about 70%. We just had the ATM virtual circuit redefined to allow an even
bigger packet size (I think the new limit is 1524 bytes). We haven't yet
re-run our performance tests to see how this affects throughput.