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

Part of the reason that helped, was it by definition rebuilt all the access paths in the library (or system). The system is smart enough to restore access paths such that they will share each other as much as possible, so it cuts down on the index maintenance as well as saving space. Access paths were laid down widest to narrowest to allow the system to share them. Smart system.

Jim Oberholtzer
Agile Technology Architects

On Mar 31, 2023, at 10:51 AM, Rob Berendt <robertowenberendt@xxxxxxxxx> wrote:

We've actually done this a few times on older systems prior to STRASPBAL.
It did help.

On Thu, Mar 30, 2023 at 1:08 PM Mark Waterbury <
mark.s.waterbury@xxxxxxxxxxxxx> wrote:

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

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