There are several other factors to consider in deciding how many domains
to use to run your applications.
- Do the applications use 3rd party libraries that need to be installed
at the domain level. If so, then those libraries will be available to
all applications in the domain, which may not be desirable.
- Do the applications uses security realms or resources that are
different for different applications? While it is possible to define
application-scoped resources or config-scoped security realms, it might
be easier to use multiple domains.
- Does the administration of the applications need to be kept separate
for any reason? Any administrator for a domain has access to all
applications in that domain. So if there are multiple administrators,
and they cannot be allowed to have access to all of the applications,
then multiple domains are the appropriate choice.
Regarding the performance of option 3, the officially supported numbers
which have been validated by our QA team are 10 clusters with 10
instances per cluster. So having 100 clusters with 2 instances per
cluster is going to be pushing up against that. Do your applications use
session failover? If not, then the group management service (GMS) can be
disabled within the clusters, and the DAS will be able to manage many
more clusters. Take into account the previous comments made about the
admin console when using many applications.
Tom