Load distribution is an application issue, not hardware. There are any number of ways to design solutions, but all would be painfully visible to the application and require application changes.
Networks are notoriously unreliable. Total stoppages lasting minutes are considered normal. Moving data from point a to point b is the issue. There is no magic. There are very good reasons why paths between a processor and DASD are so fast. And why there are layers upon layers of buffering/caching in an I/O subsystem. While data can be quickly moved between two distant datacenters, it should not be thought of as shared DASD. Not even close. So, yes, even a micro second is a very, very big deal in this context. We have such a project underway. GDPS does not look to be applicable to our online systems. I think it unremarkable that there are few (if any) shops are deploying this option. HTH and good luck. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Clark Lowery Sent: Wednesday, September 28, 2005 3:18 PM To: [email protected] Subject: Geoplex performance considerations We are beginning the construction of a third data center, and I've been tasked with developing our mainframe configuration plan. I would like to run a true data sharing Geoplex (hot/hot, with load distribution done by our foundry devices behind the WEB servers). In talking to IBM, I've been given data about how elapsed time increases by kilometer across fiber, and warned about CF delays if we go more than a kilometer or two. While the physics of the latency are clear, what I'm not convinced of is the impact on my users. Since total DB2 processing is a very tiny portion of the overall service time, I can't see any latency measured in microseconds impacting users. BUT... What do I have to watch out for internal to DB2 and z/os? For example, will I need more capacity to handle overhead lock management costs? I've received some help for a few people who've done something similar, but we'll be using EMC for data replication and I've found no one running a Geoplex supported by EMC's SRDF/A. Any help would be greatly appreciated!!! ---------------------------------------------------------------------- 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
