Memory overhead associated to SNA Server is minuscule in comparison to other Microsoft BackOffice applications. (SNA protocol was designed to fit in 32K cluster controllers!) Accordingly, the following memory sizing recommendations and associated processors are recommended:
# Users |
Amount of RAM |
Processor |
<= 500 |
32 MB |
66 MHz 486 |
<= 2000 |
64 MB |
90 MHz Pentium |
SNA Server consumes CPU (and interrupt-handling) resources, not disk. You should tune the server to cause basically no paging due to SNA process faulting. You can achieve this via the Process: Page Faults/sec Performance Monitor counter. If this value is high for any of the SNA Server processes, consider adding more memory to the system, or examine the Microsoft BackOffice architecture for other processes using extensive memory.
You should not run the SNA Server at 100% CPU, and should monitor Processor: % Privileged Time in order to reduce the interrupt latency. If this Performance Monitor counter is high then SNA Server may be performing poorly.
In order to improve interrupt processing, you may consider acquiring a 32-bit bus master network interface card. This will help to offload network interrupt handling from the system processor(s).
On heavily loaded SNA Server systems it may be beneficial to load balance the network and SNA traffic onto separate network interface cards.
You can load balance user connections over several SNA Servers by creating a LU pool that contains LUs from more than one SNA Server. The load will be shared according to the number of users per SNA Server.
You can get a good idea of how heavily loaded the server is from an SNA perspective by monitoring the SNA Connections: Throughput Bytes/Sec counter. This counter shows both incoming and outgoing bytes on a connection basis.
It is easiest to improve SNA Server performance by adding additional or faster processors.