If you measure the resource util on the apache boxes while under load,
you may find that you can get by with A single apache instance and 4 tomcat
instances (each on it's own box).
You may be able to but you lose the ability to load balance across the
Apache instances for high-availability.
It does depend on the balance of the workload between the apache and
tomcat. The tomcat/jvm generally needs a lot of cpu.
In many regards this isn't an issue for either layout because if it is
found that the load is too much one just adds another server. But this
does raise a valid argument for the N + M configuration as it allows for
different hardware to be deployed for Tomcat e.g. more RAM or a second
CPU. However most larger deployments prefer to maintain a standard
server build for all servers and simply use server count to increase
capacity in which case I guess the flat single tier is preferable.
Are you going to store the tomcat content N times (once per box) or use
a single instance of shared storage?
The option for data management really depends on the type and volume of
data. Load balancing NFS can be problematic and clustered filesystems
expensive but it may be the best solution. Syncing out data files (e.g.
XML) to each server is another alternative. This is really very
dependent upon the nature of the application and type of the data.
Another option some may use is a central DB from which local files are
generated based on access or a background task.
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
