> -----Original Message----- > From: McKown, John [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 26, 2007 12:07 PM > To: [email protected] > Subject: VSAM in extents > > I'm curious about this one. A person here has stated that when a VSAM > KSDS file is in multiple extents, it performs more poorly than it would > in a single contigueous extent. He said something to the effect that > when a portion of the index is referenced which is in "another extent" > that the entire in-memory buffer for the file is flushed. I have no idea > where he got this information.
Hmm-m-m. I guess that might possibly be true for small numbers of buffers, but in my experience it's demonstrably NOT true when using SUBSYS=(BLSR...) or the newer SMB facility (AMP='ACCBIAS=...'). With sufficient in-memory buffers, there should be no or little distinction between one or many extents. Might this be knowledge that dates back to real SLED devices and constrained memory environments? Peter This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- 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
