05-27-04 04:30 AM
Ken Hygh <kenhygh@nc.rr.com> wrote in message news:<c92ad5$4386$1@news.boulder.ibm.com>...[v
bcol=seagreen]
> Frank A wrote:
>
> Make sure that the sum of the max heap sizes of all JVMs is smaller
> than the physical memory. A swapping JVM is a terrible.
>
> Network Deployment vs. standard: you can do clustering of the same app
> across multiple JVMs, whether on the same machine or different machines.
> You can get failover and workload management. If all you have are single
> instances of apps/JVMs, then you get a single point of administration.
>
> Ken[/vbcol]
Just to follow-up; When we talk about Network Deployment it's actually
a product packaging of WebSphere Application Server, called
(surprisingly) WebSphere Application Server v5 Network Deployment
(usually also called WAS 5 ND). There's no such thing as a "standard
deployment", but there's a product packaging called WebSphere
Application Server v5 (usually also called "WAS 5 Base").
If you would deploy multiple applications, each in its own JVM, on one
single machine you could either use only WAS v5 Base or WAS v5 Base &
WAS v5 ND. The ND packaging would give you easier administration
(start/stop/install etc.) but you could do the same with Base. If you
would only use Base you would have to install the Admin Console (an
EAR file) into each JVM you would like to manage (so each JVM would
host both adminconsole.ear and your app). It's certainly doable but
when having multiple JVMs (regardless if they are on a single machine
or on multiple machines) WAS v5 ND is usually the way to go.
If you would like to scale the solution by using clusters you would
need to use WAS v5 ND as that functionality is only in ND. Cluster can
be created either within a physical machine (vertical clustering)or
between physical machines (horisontal clustering) or both. Since you
already have multiple JVMs on each machine in your case it would make
most sense to scale horisontally to get fail-over capabilities as well
as increased capacity.
Deploying each app into its own JVM is fairly common and it gives you
some flexibility when configuring the app. You can e.g. set
environment variables, JVM heap sizes and other tuning parameters on
each application. However, since you have multiple JVMs you will need
more memory than if you deploy your apps into one or perhaps just a
few JVMs.
Henrik Sjöstrand
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