Re: [U2] Unidata Caching
The version of DB and O/S might help? Remember to do your testing in a live like environment. Running a test at night with no one else on the system won't point out any short comings that will become obvious when 30+ users start whacking at it. Always assume the worse. And then add another 50% to your estimates. Jeffrey Butera wrote: Can anyone shed insight on how/what Unidata does for caching? In short, I notice that when I perform some SELECTs or programs which read a handful of records, they often run faster after first execution - I'm assuming Unidata is caching. I was working on adding some caching to an application I'm working on but if Unidata is already doing a reasonable job I may not see any sizable performance difference (and don't want to spend many hours working on this to find it's in vain...) Any insight appreciated. --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
RE: [U2] Unidata Caching
Does RFS manage virtual paging - or is it just a block of memory? -Original Message- From: Wally Terhune [mailto:[EMAIL PROTECTED] Sent: Wednesday, May 03, 2006 9:53 AM To: u2-users@listserver.u2ug.org Subject: Fw: [U2] Unidata Caching Unless you are running RFS (for which we have a our own cache in shared memory), you are likely just experiencing the OS file system cache and or disk RAID array cache... Wally Terhune U2 Support Architect IBM Information Management 4700 South Syracuse Street, Denver, CO 80237 Tel: 303.773.7969 Fax: 303.773.5915 [EMAIL PROTECTED] - Forwarded by Wally Terhune/Denver/IBM on 05/03/2006 07:51 AM - Jeffrey Butera [EMAIL PROTECTED] e.edu To Sent by: U2-Users New Lists [EMAIL PROTECTED] u2-users@listserver.u2ug.org stserver.u2ug.org cc Subject 05/03/2006 06:42 [U2] Unidata Caching AM Please respond to [EMAIL PROTECTED] er.u2ug.org Can anyone shed insight on how/what Unidata does for caching? In short, I notice that when I perform some SELECTs or programs which read a handful of records, they often run faster after first execution - I'm assuming Unidata is caching. I was working on adding some caching to an application I'm working on but if Unidata is already doing a reasonable job I may not see any sizable performance difference (and don't want to spend many hours working on this to find it's in vain...) Any insight appreciated. -- Jeff Butera, Ph.D. Administrative Systems Hampshire College [EMAIL PROTECTED] 413-559-5556 We're not given the burdens we deserve, we're given the burdens we can bear. Several --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ [demime 1.01d removed an attachment of type image/gif which had a name of pic04086.gif] [demime 1.01d removed an attachment of type image/gif which had a name of ecblank.gif] --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
RE: [U2] Unidata Caching
Does RFS manage virtual paging - or is it just a block of memory? The RFS system buffer is a chunk of shared memory that keeps track of records read from and/or updated to recoverable files. In other words, it's maintained at the logical record level. If a requested record is found in the system buffer, no attempt is made to retrieve the record from disk. I/O to non-recoverable files goes straight to the O/S I/O routines, just as when RFS is not active. Tim Snyder Consulting I/T Specialist , U2 Professional Services North American Lab Services DB2 Information Management, IBM Software Group 717-545-6403 [EMAIL PROTECTED] --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
RE: [U2] Unidata Caching
This good to know. RFS should speed things up then. Do you know what the paging mechanism is, when the shared memory gets full? LIFO, block (record) stats... -Original Message- From: Timothy Snyder [mailto:[EMAIL PROTECTED] Sent: Wednesday, May 03, 2006 11:32 AM To: u2-users@listserver.u2ug.org Subject: RE: [U2] Unidata Caching Does RFS manage virtual paging - or is it just a block of memory? The RFS system buffer is a chunk of shared memory that keeps track of records read from and/or updated to recoverable files. In other words, it's maintained at the logical record level. If a requested record is found in the system buffer, no attempt is made to retrieve the record from disk. I/O to non-recoverable files goes straight to the O/S I/O routines, just as when RFS is not active. Tim Snyder Consulting I/T Specialist , U2 Professional Services North American Lab Services DB2 Information Management, IBM Software Group 717-545-6403 [EMAIL PROTECTED] --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ --- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
