Re: DTACPR(*YES) COMPACT(*DEV)

[Neil Palmer <neilp@xxxxxxxxxxx>]

By specifying *DEV you let the system determine whether the tape drive or 
the IOP support compression or compaction and utilize the most efficient 
method.  Specifying both is like compressing a file twice - you can end up 
making it larger the second time.  Some people may have specific reasons 
for using one or the other, so teh command gives you the choice.

...Neil





D.BALE@handleman.com
Sent by: owner-midrange-l@midrange.com
2001/05/23 11:37
Please respond to MIDRANGE-L

 
        To:     MIDRANGE-L@midrange.com
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        Subject:        DTACPR(*YES) COMPACT(*DEV)


Thanks again, guys!  (Re: 6390 data capacity)

Thankfully, we have no -002 versions of the 7208 drives, only -012 and 
-222
versions.

Per my earlier question of the DTACPR & COMPACT parameters:

Do I understand correctly that DTACPR(*DEV) COMPACT(*DEV) will not use
compression when the tape device supports compaction?  Why wouldn't you 
want
to do that?  If DTACPR(*DEV) COMPACT(*DEV) is always the best to use, why 
does
IBM allow us to specify DTACPR(*YES) COMPACT(*DEV) ?

- Dan
Dan Bale says "BAN DALE!"
IT - AS/400
Handleman Company
248-362-4400  Ext. 4952
D.Bale@Handleman.com
  Quiquid latine dictum sit altum viditur.
  (Whatever is said in Latin seems profound.)

-------------------------- Original Message --------------------------
Assuming an older 7208-002 is capable of using the thinner 160m tape
without jamming or wrapping it around the head drum, it would get about
3.5GB (uncompressed) on the tape.  Newer drives can use *FMT7GB (which is
the same format as *FMT5GB but on a longer tape).

The chart you refer to in the handbook is incorrect (I had already
notified IBM).
As you noticed, the 6390 info is duplicated from the 4587 QIC drive above.

It's best to use both DTACPR(*DEV) COMPACT(*DEV) to get the most data onto
the tape.

...Neil
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