Re: Do any of you have a policy on rebuilding indexes?

Hi, Patrik,

For V3 and earlier, without STRASPBAL, I learned from the late great Al Barsa Jr. that you can "defragment" the entire system only by doing a full GO SAVE 21, followed by IPL from the tape, and choose the option to "Load and initialize" -- this will re-load all of the objects, in a way that is now defragmented.

You can also "defragment" on a library-by-library basis, by doing a SAVLIB (to a save file), then delete the library, then RSTLIB from the save file.  This also still works, right up to the very latest versions of OS/400 / IBMi.

Mark




On Thursday, March 30, 2023 at 12:18:36 PM EDT, Patrik Schindler <poc@xxxxxxxxxx> wrote:





Hello Jim,

Am 30.03.2023 um 17:33 schrieb Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>:

If there is an imbalance of disk utilization IBMi will over time balance that out all on its own.

Imbalance over disk arms has nothing to do with fragmentation. See here for a discussion of the issues:

https://en.wikipedia.org/wiki/Fragmentation_(computing)#Performance_degradation

That's not to say that files themselves can't be degraded due to deleted records.

This is also not related to fragmentation per se.

Most access paths are set to immediate update, so if there are ones that are not in use, it helps to get rid of them to lessen overhead, but again on current systems I doubt that will have much of an effect on performance.

That obviously depends heavily on write/update usage.

If disk units were added to an existing system we would run STRASPBAL for capacity and the system would then move things around based on its own understanding.

Still not related to fragmentation. :-)

On your system even though it is older you would be able to see these things in action if you are able to add a drive.

I know. Experimented with that a bit. Unfortunately, V3 and earlier has no STRASPBAL. :-)


:wq! PoC