Yeah, but in this case it's the wrong book.
With Oracle dropping support for their products on z/OS, the only
mainframe platform now supported is Linux running as a guest of z/VM (or
in an LPAR, I suppose). I think we'll soon see more z/VM-Linux specific
performance guidelines from them in the future.
Also take a look at the International zSeries Oracle Special Interest
Group (SIG) which is focused on running Oracle applications and
databases on zseries hardware. It can be found here:
http://www.zseriesoraclesig.org/
They have all of their conference presentations available online,
including the ones from our very own Barton Robinson.
On 02/04/2010 09:02 AM, Ron Wells wrote:
sounds familiar>> the book tells them to..
From: "van Sleeuwen, Berry"<[email protected]> To:
[email protected] Date: 02/04/2010 08:32 AM Subject: Re: A
Question on Sizing z/VM Linux Guests Sent by: Linux on 390
Port<[email protected]>
We have some oracle guests that have been set to 1G. And they
actually need only 300M. The rest is occupied in cache (between 650
and 710M). I'd like to decrease the machines but it is quite hard to
convince the oracle group that the machines do not need the memory.
Instead, they even want to increase to 2G because the books tell
them to. While the documents suggest the oracle will benefit from
the increased memory, in reality VM will page more and the effect is
an overall decrease in performance for all guests.
I would suggest to keep the guest as small as possible. Also try to
limit SGA and such.
Berry.
-----Original Message----- From: Linux on 390 Port
[mailto:[email protected]] On Behalf Of RPN01 Sent: donderdag
4 februari 2010 14:17 To: [email protected] Subject: Re: A
Question on Sizing z/VM Linux Guests
If you're using IBM style DASD as your disk storage, you'll want to
size the linux image's memory considerably smaller than what is
suggested for an Intel processor.
The first reason is that you have several levels of cache before the
data even gets to the linux image. These layers (controller, z/VM,
mdcache) will cut the time to retrieve the data, and caching it in
linux as well really won't make anything any faster.
The second reason is that larger images cause more paging on z/VM's
part. The Intel memory suggestion is based on real memory, always
available. Since this is virtual memory, your "in-memory cache" may
actually be on disk anyway, causing a paging read when it is needed.
You can actually slow down the response in an image by making its
memory larger, because it will spend much more time paging.
Finding the right size is a little more tricky. You want to start at
some reasonable value (1G, 2G...), and then cut the image's memory
over time until you notice it just begin to swap. Some people will
allow it to do this minimal swapping, while others will increase the
image size enough so that it doesn't swap at all. It just depends on
which expert you choose to listen to.
At this point, you'll have an image that supports the application
running, but doesn't have enough memory to devote a large amount to
caching its disk, which is exactly where you want to be. You may
actually be surprised at how little memory this really is.
-- Robert P. Nix Mayo Foundation .~. RO-OE-5-55 200
First Street SW /V\ 507-284-0844 Rochester, MN 55905 /(
)\ ----- ^^-^^ "In theory,
theory and practice are the same, but in practice, theory and
practice are different."
On 2/4/10 7:00 AM, "Carson, Brad"<[email protected]> wrote:
We have a project that is being setup to run on RHEL under z/VM.
The sizing parameters for the guests (Oracle DB, and WebLogic) are
being sent to us based on intel platform sizing. How do some of
you handle the sizing conversion from Intel to IFL's? Are there
some rules of
thumb, we should know about?
Our environment:
IBM z10-BC (QA and Dev) and z10-EC (Prod) running z/VM 5.4 and
RHEL
5.3.
Thanks for any insight.
/Brad (please ignore the company inserted HIPAA disclaimer)
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