On 11/06/2012 05:13 AM, Paul Gilmartin wrote:
On Tue, 6 Nov 2012 01:05:50 -0500, Sam Golob wrote:
     Further, if, when you copied an SL tape to NL with COPYMODS using
PARM=STRIP, and you also dumped the images of all the labels using
PARM=LABLDUMP at the same time, you can then RECONVERT the NL tape back
to an SL tape, by sandwiching the dumped labels back, using the
PARM=LABADDIN option of COPYMODS.  So you can go SL to NL, and then NL
to SL for an entire tape, with many files. Further, if you want to
change some of the labels in the meanwhile, you can edit the dumped
labels before splicing them back on the NL tape using a PARM or SYSIN of
LABADDIN under COPYMODS.  Cool?

Will this round-trip conversion work correctly even if the original
SL tape contained several empty data sets?

Does COPYMODS support changing the VOLSER in both the VOL1 and
HDR1 labels?

-- gil


"Empty" tape data sets shouldn't pose any special problems, as they are not empty in the 
NULL sense but still contain an EOF "tape mark" on the tape after the optional physical 
data blocks and can be represented unambiguously by just an EOF mark on either NL or SL tapes.  The 
only difference is that a SL tape contains two additional physical files for each logical file, 
each also terminated by a tape EOF -- header labels in front and trailer labels behind the physical 
data file.

As long as you have some way to supply the data set descriptive info needed for the label 
records, going from NL to SL isn't made any more difficult by an empty file.  Having 
actual data may make it possible to verify that "known" data set attributes are 
consistent, but would in general be inadequate for unambiguously determining the correct 
data set attributes if they are unknown.
--
Joel C. Ewing,    Bentonville, AR       [email protected] 

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