I have enjoyed the responses to these questions I posed regarding what is
a transaction. So to continue, I was asked, " what are the JVMs doing?"
In most cases are JVMs are little utilized, they all run in the wonderful
world of WebSphere thus they all communicate to a Database and to an LDAP
(Secureway most likely). In they end they all perform different
functions, some go through the process of managing users and their web
access and web privileges, some deal with business centric stuff. Again,
though they are generally under utilized in the wonderful world of Solaris
systems. But then again it is hard to over utilize a SunFire 480 with 4+
GB of Memory. So I guess I can't really answer this question, but what I
can say is our developers need to be more talented when it comes to
developing reliable java code. It seems there are many JVMs in our
environment that will exceed the initial HEAP size of 128 MB, thus at
~129, the JVM pulls another 128 MB of memory into its little world. What
impact if any would this behavior have in an environment where you z/VM w/
25 guests each running some number of JVMs and most of these JVMs start
grabbing memory? Will one guests JVM growth impact another system's
attempt or ability to grab more memory for its JVMs?
thanks
Eric Sammons
(804)697-3925
FRIT - Infrastructure Engineering
David Boyes <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <[EMAIL PROTECTED]>
10/28/2003 02:05 PM
Please respond to Linux on 390 Port
To: [EMAIL PROTECTED]
cc:
Subject: Re: Perpetuating Myths about the zSeries
> Well my question then is, what is a
> transaction?
A very good question, and exactly why the "how many PCs can I
consolidate?"
question is basically a useless one. The answer has to include what the
PCs
are doing and how they do it. It's comparing apples and pumpkins.
> So what is a transaction?
The best definition I've come up with is a seqence of operations that
accomplishes a single unique unit of business typical to an application,
defined by the type of problem and type of application.
> Would I want to
> run 100 systems in a given z/VM each with some number of JVMs, yes
> WebSphere?
What do the applications running in the JVMs do? 8-)
> On the topic of availability I am not sure I buy the whole MF
> is better
> than 80x86 or Intel / AMD 64 server hardware. Today, everything is
> redundant and everything is hot swapable.
But not to the point of being able to intercept failed instructions and
re-dispatch on pre-installed spare hardware, unless you've bought a really
Tandem or some such system, at which point you're not paying much less
than
the equivalent zSeries. Correcting failure in flight isn't yet possible in
Intel hardware systems, and even with the Opteron and Itanium, it won't be
easy. None of the Intel systems share instruction pipelines yet.
Now if some of the rumors about using a PowerPC core for the next gen
zSeries processors are true, or that IBM licenses some of the PowerPC or
zSeries multicore fab technology to AMD or Intel to make MCM-style
platters
of Intel engines, that might change the picture drastically. I don't see
that happening, but it'd be a very interesting change in the landscape.
> What is different
> is to get a
> new stick or replacement stick of memory for the MF could cost you and
> automobile and you won't find that stick of memory at the
> local computer
> store.
No, you'll find your IBM CE showing up at your door with the correct
replacement in his hand before you even know it failed...8-)
-- db
