Running multiple Application Servers raises the same
issues as running multiple SAS sessions. There is little to be concerned
with if you set up each server on a different file system. However,
quite often, multiple servers could be set up that access the same
file system. This raises the general issue of file contention between
the Application Servers.
Here are some guidelines
to follow if you set up multiple Application Servers on the same file
system:
-
Servers can share a server root
directory.
-
Servers can share program libraries.
Be sure to use
access=readonly when allocating
shared program libraries. Allocating shared program libraries in this
way prevents an Application Server from opening SAS catalogs in update
mode.
-
Servers on the same machine must
use different port numbers.
-
Update access to data sets should
be done through the use of
SAS/SHARE software. If you do not use
SAS/SHARE
software and two users attempt to update the same SAS data set at
the same time, a failure results.
-
Because update access to files
can fail due to operating environment contention, Application Dispatcher
programs should be prepared to handle such failures.
-
Each server should write to a different
log file.