Ted,
Actually, you were correct originally. Ring works between systems in an
environment that has a sysplex and systems outside the sysplex. It is Star
that works only within a sysplex. In fact, if you have only a sysplex,
there is almost zero reason to use Ring and IBM strongly recommends Star in
this situation.
A Ring in his environment might not be so bad, depending on the how Gray
sets it up. He could significantly lower the RESMIL value to improve
performance (IBM recommends RESMIL of 0 for an environment such as his
without Ring Acceleration). There would be a little more overhead, but
perhaps he can afford the overhead as a trade-off for better
performance. Also, he could use ACCELSYS(2) to gain a significant
performance benefit in his Ring.
I'm not saying that he should go with Ring rather than staying with MIM,
but sometimes you do what you have to do. If money is really tight,
perhaps Ring would be acceptable. I do suggest that Gray carefully review
the considerations outlined in the MVS Planning: Global Resource
Serialization document before making his decision.
Don
******
Don Deese, Computer Management Sciences, Inc.
Voice: (804) 776-7109 Fax: (8043) 776-7139
http://www.cpexpert.org
******
At 03:47 PM 3/24/2009, you wrote:
>We have a monoplex, a Sysplex(5 lpars) and a Sysplex(2 lpars) that share
DASD.
Sorry, I misspoke a bit.
When I said GRS-Ring was okay between two SYSPLEX's, I was wrong.
It's between images.
Since the GRS token has to be passed to each image to ensure global ENQ's,
the more the worse the response.
GRS* only works within a single SYSPLEX.
MIMgr works because (as long as the CDS is not in a CF), every system
talks directly with the master system (oldest IPL), so there is only
passing of data between the requester and the master -- no passing around
a ring.
The ring is the bottleneck, and you have eight systems -- way to many!
If you can afford the fees, I'd stick with MIMgr in your config.
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