Adding cache to an existing storage processor without an identified performance problem you will solve is going to be hard to justify and amounts to brain surgery on your existing box that has some amount of risk. Tools http://www.intellimagic.net like RMF MAGIC and DISK MAGIC can actually show you what is happening now and what would change if you added that cache and it may not be what you would expect. There may be other tools that can do this kind of thing but those are the ones I am aware of.
I think the 2105 is a dead end at this point. You would probably be better off to spend time trying to bring in a DS8000. http://www.ibm.com/systems/storage/disk/ds8000/ The performance and functional improvements from 2105 to 2107 are dramatic. You will likely get much more benefit spending the money that way than adding cache to a previous generation storage processor. Cache is just one element of performance and the next generation includes improvements in all aspects of the storage processor architecture. You might be able to get IBM to run a DISK MAGIC study for you to show you the result of adding that cache or replacing your 2105 with 2107 technology. We are pushing the 2105's off the floor as quickly as we can migrate the data to 2107 on both open and z/OS. I am sure other DASD vendors would say replace the 2105 with my model xyz which would also be a valid proposition. The point is don't spend money on old technology bring in current and get more bang for the buck no matter what vendor you use. Best Regards, Sam Knutson, GEICO System z Performance and Availability Management mailto:[EMAIL PROTECTED] (office) 301.986.3574 (cell) 301.996.1318 "Think big, act bold, start simple, grow fast..." -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Alvaro Quintupray B. Sent: Wednesday, November 05, 2008 9:03 AM To: IBM-MAIN@BAMA.UA.EDU Subject: How do I justify an investment in Cache? Hi. We have disk 2105 - F20 with 5,2 tera of storage and 4 Giga cache size by cluster we want to come to 8 Giga in every cluster but the increase of Cache Storage is very expensive... Now, my chief says to me ... it improves the performance of the machine if we have the cache doubles ..? how can we quantify it? Thanks. ==================== This email/fax message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution of this email/fax is prohibited. If you are not the intended recipient, please destroy all paper and electronic copies of the original message. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
