Peng Tuck Kwok wrote:
Probably the reason why he's seeing one instance of tomcat moving quicker
than 2 instances is the fact that there is some form of contention for
resources on that single machine assuming that the 2 instances are
configured identically in every aspect (other than ports).
You mis-read it. He's seeing twice the performance from two instances
than he is one single one, which shouldn't be if the one is properly
configured, (with the exception noted below).
D
The idea is not to give you a 0-60 mph capability with 2 tomcats on a single
box (partition) but to give you better throughput. As I understand it, when
you start getting more load, you'd be able to handle the requests in a
linear fashion (again assuming you've sized the 2 or more instances
correctly).
*>I would rarely recommend that a client run parallel app servers on the
same machine for the same application for any purposes other than being
able to switch between versions of the same application (say, for
zero-downtime upgrade strategy).
*I wouldn't recommend anyone do that just to switch versions for a zero
downtime upgrade strategy as well. Some sort of DR would be better for this
? Down production and switch to DR then when upgrades are complete just
reverse what has been done.
*>Since the OP didn't say that's what his
requirements were, there doesn't seem to be a compelling reason to use
this strategy.
*You're right, until we really know what his requirements/KPI's on that are
then most of this is largely academic.
Nishi, the link to the redbook is here
http://www.redbooks.ibm.com/abstracts/sg246392.html?Open .
It's websphere specific, but there's still lot of things you can pick up on
and probably apply.
On Wed, Nov 12, 2008 at 5:15 AM, Christopher Schultz <
[EMAIL PROTECTED]> wrote:
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Pengtuck,
[EMAIL PROTECTED] wrote:
So let me get this straight. You are reluctant to accept a
configuration which gives you improved throughput ? :P
No, the OP is unwilling to use a configuration that doesn't make any
sense: one single Tomcat should outperform two Tomcats on the same
physical server (unless you are talking about a 32-bit JVM that needs a
lot of memory).
Anyway, this is not an unusual approach, from what I understand this
simply makes full use of the resources available on that machine. Not
uncommon in real world to see app servers like websphere being
configured in that manner.
I would rarely recommend that a client run parallel app servers on the
same machine for the same application for any purposes other than being
able to switch between versions of the same application (say, for
zero-downtime upgrade strategy). Since the OP didn't say that's what his
requirements were, there doesn't seem to be a compelling reason to use
this strategy.
- -chris
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