Re: Dynamic Cache Management

[John Kington]

GSG,
I was reading the Implementing System-Managed Storage book and came
accross Using Cache to improve performance, were it spoke about Dynamic
Cache Magagement.  Is there still a benefit in implementing this?
PROS/CONS.  Is anyone using this?  Got any general guidelines for starting 
out?

I never bothered with DCM(E) since all data written to/read from modern dasd 
subsystems went though cache anyway. It is very complex sometimes trying to 
figure out why allocations are occurring against certain volumes and not 
others. DCM(E) just added another complicating factor that did not seem to have 
any significant benefit in performance.
Your mileage may vary.
Regards,
John

--
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO
Search the archives at http://bama.ua.edu/archives/ibm-main.html

Re: Dynamic Cache Management

[Ron Hawkins]

GSG,

For IBM, SUN/STK and HDS there is still a small benefit. While everything
must go through cache with these controllers, DCME will influence where ICL
and BC IO is placed in the LRU queue so that it will be cast out sooner than
other normal IO.

You don't get a choice about whether it is implemented or not. DFSMS will
use the MSR value in the STORCLAS to decide whether the dataset is Must,
Maybe or never cache.

Ron

 -Original Message-
 From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On
Behalf Of
 gsg
 Sent: Thursday, September 10, 2009 3:08 PM
 To: IBM-MAIN@bama.ua.edu
 Subject: [IBM-MAIN] Dynamic Cache Management
 
 I was reading the Implementing System-Managed Storage book and came
 accross Using Cache to improve performance, were it spoke about Dynamic
 Cache Magagement.  Is there still a benefit in implementing this?
 PROS/CONS.  Is anyone using this?  Got any general guidelines for starting
 out?
 
 TIA
 
 --
 For IBM-MAIN subscribe / signoff / archive access instructions,
 send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO
 Search the archives at http://bama.ua.edu/archives/ibm-main.html

--
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO
Search the archives at http://bama.ua.edu/archives/ibm-main.html