Re: V6R1 to V7R1 i5/OS DSLO image upgrade issues

On 27-Mar-2014 06:21 -0700, Steinmetz, Paul wrote:

I saw a disk savings of 2%, or 58 gb.
My V7R1 LPAR is smaller than my V6R1 LPAR

So as I infer: An LPAR that was at v6r1, was upgraded to v7r1, using the DSLO, and now the overall storage on the since-upgraded LPAR requires 2% less space.

A followup reply had suggested that "I actually did NOT permanent apply the V6R1 PTFs."

Seems likely that the storage from the excess, effectively duplicate OS code [i.e. two copies of each program as part of a PTF, many of the copies being created from a different revision level of the source code] that remained on the v6r1 partition were deleted as part of the upgrade rather than as part of the pre-upgrade processing. Probably a good portion of that 2% gain would have been achieved while on v6r1 if the perm apply processing had been done there.

Another thing, is that the code from media should have been /compressed/ and remain compressed for some time since the install completes. Thus had the v6r1 system been up and running for some time and actively being used, the various OS objects likely had since been decompressed on that release. The newly installed v7r1 with compressed objects would slowly decompress those same objects over time, and any portion of the storage gain from those compressed objects would be getting pared down over that same period of time.

FWiW: I actually can not recall how the OS deals with those PTFs that were not permanently applied, but I expect they would have been processed by the upgrade similarly to what the perm apply would have effected, even if not updating the PTF database to reflect the effect. The OS could, to get back much of the excess storage, effect blindly, each of DLTPGM QSYS/QPZ* and DLTSRVPGM QSYS/QPZ*; i.e. even deleting the OS objects with that same naming convention would be little harm, because the restore for install would get all necessary code onto the system from the media. Any previous-release PTFed programs are wholly unnecessary for the operation of the new OS, so their loss is of no consequence to the newly installed OS.

FWiW: Might be worth reviewing the history log and SCPF joblog from the install for various "deleted" messages, to see if anything unexpected was deleted during the install. If for example one of the larger system database cross-reference files was deleted due to an error :-( then that could /recover/ a notable amount of storage, but the effect would be temporary, pending the condition being recovered by a reclaim of the *DBXREF.