Re: Compress Object command

[Tom Liotta <qsrvbas@xxxxxxxxxxxx>]

Mike Cunningham wrote:

> Early this week I had asked about using the CHGPGM command to remove
> observability and compress program sizes that all responders said to
> forget about. One mentioned using the Compress Object CPROBJ command to
> save on space usage and speed up backups. Is anyone using this command
> on a regular basis to reduce the size of objects that can be compressed
> that only get used infrequently like year-end processes? If you do run
> it do you only compress your own objects or do you do a system wide
> compress? 

Mike:

I run CPROBJ under various circumstances and get excellent results, 
especially when I want to create savefiles to ship to other systems. 
As you found, it only works on some object types; but it can do very 
well for the objects that work.

Keep in mind that it's a _temporary_ compression and that it can 
technically increase the amount of storage in use on your system 
under some odd circumstances. That's because both temporarily 
decompressed versions of the objects can exist at the same time as 
the compressed versions. (Usually that's only a few of the various 
objects at a time.)

However, I'm not yet clear on why you wouldn't use CHGPGM RMVOBS() 
first. Did you actually test it?

I can get a lot of space savings in *PGM objects via RMVOBS() at 
least up to V5R3, both OPM and ILE. And it's not 'temporary' in the 
same sense as CPROBJ.

Note that you can chose RMVOBS(*ALL) or some subset of 
observability, particularly for ILE programs. Also note that some 
creation data might be retained for programs created V5R1 or later 
regardless of what you specify. When you remove observability, you 
must recompile to get the observability back if you need it.

Tom Liotta

> I am considering running this CPROBJ OBJ(*ALLUSR/*ALL) OBJTYPE(*ALL)
> DAYS(90) every week end when system use is low.  Or would CPROBJ
> OBJ(*ALL/*ALL) OBJTYPE(*ALL) DAYS(90) be a better choice.
>  
> I did a test on our development library which has 2,915 objects. 2,901
> were scanned by CPROBJ, 464 were able to be compressed and space usage
> for the library went from 3,924,838,912 down to 3,833,350,656. Not a big
> change.  But, of the 464 objects that were compressed space usage went
> from 150,269,952 down to 58,781,696. Not bad.