[7.3] IFS save 21 vs. sav with chgperiod (no BRMS!)

Hello,

I'm still learning about establishing a meaningful save routine for a (to me) newer 7.3 installation to a remote NFS based optical image catalog.

The backup concept is basically:
- do a save 21 "now and then" (manually),
- run savchgobj updhst(*no), savdlo dlo(*chg) updhst(*no), and sav chgperiod(*lastsave) updhst(*no) each night.

That's how I'm doing that on my V4R5 box to tape and that saves only things which have changed since the last Save 21. I'd expect that to behave similarly on newer releases.
Goal is being able to copy the last Save 21 image to the VIOS image catalog, IPL from that and restore LIC, system and other objects, including DLO and IFS. Afterwards, restore the last differential saves from the remote NFS device.

I'm observing that a huge load of files from the IFS is being saved over and over again. Nearly 1.3 GB of objects duplicated needlessly, day after day, because they have not changed since the last Save 21 and hence should not be eligible for ending up in a sav chgperiod(*lastsave) updhst(*no). Note: I'm not actively using the IFS, yet. Nor do I use /QDLS. But I want to save everything because it makes restores easier. No need to think about further manual steps.

That's my sav command line:

sav dev('/qsys.lib/optbkup01.devd') obj(('/*') ('/qsys.lib' *omit) ('/qdls' *omit) ('/qntc' *omit) ('/qfilesvr.400' *omit)) output(*print) chgperiod(*lastsave) updhst(*no)

Apparently, (certain?) IFS objects aren't saved, or not being flagged as "have been saved" through a Save 21. Haven't checked that, yet. I dimly remember that the topic about a "special flag" for IFS objects regarding saves has been discussed here in the pastime. Can't remember details, so I can't search for that.

With my current knowledge, allowing Save 21 to save the complete IFS seems to be the way to go, because I don't intent to reinstall the OS from scratch after a catastrophic failure, but IPL and restore from backup, see above.

Can anyone shed some light on the "correct" approach? And/or what to do about the apparent fact that a full system save seems to not save *everything* on that system?

Thanks!

:wq! PoC