RE: ADSM Network Impacts

Unfortunately, "It depends" is the answer and if you are considering a
significant expansion of your ADSM customer base, a thorough analysis of the
expected customers and  potential network impacts is required.

As many of the responses have pointed out, individual users updating files on
their workstations will not generate a significant amount of incremental
traffic.

However, if you are backing up LAN file servers that contain databases, the
amount of incremental back-up traffic could be significant.  This is
especially true if the database software does not happen to have an ADSM
"add-on" to provide incremental back-up functionality from the database.(e.g.
SQL-Backtrack for Oracle).  For example, if you are running Lotus Notes on an
NT server, there is not a Notes agent so if a Notes users receives even one
new e-mail message, the entire Notes database will be backed-up.  This can
generate a significant incremental back-up workload.

Another factor you must consider is the type of processors that will be
generating the back-up traffic.  In benchmarks I have seen, the rate of data
flow from a particular server or workstation was dependent on the workstation
CPU speed.  For example, a dual processor server with 200MHz processors can
throw back-up data into the network much faster than an older server with one
processor running at 66MHz.

You must also consider the network infrastructure and interface that is
attached to the server that is providing your ADSM Server function.  For
example, if the ADSM server is attached to the rest of the network by a single
16Mbit token-ring segment, then your overall throughput will be limited by the
token-ring speed.  Make sure you understand the throughput limitations of your
interface.  For example, some of the older 3172's used to provide an IP
interface to S/390 systems cannot process much more than about 1.3MB/sec.
Newer 3172's or Cisco routers with Channel Interface Processors will provide
ample bandwidth into a host.

One customer I work with has created a back-up network to provide bandwidth
that was suitable for their back-up workload and to ensure that any daytime
restores would not impact shared network segments.

In summary,

1. It depends.
2. Know your workload.
3. Make friends with your network engineers.


Taylor Mitchell

Taylor_Mitchell AT msn DOT com