At 1:49 PM -0800 2/12/06, Craig Lalley wrote:

>Alfredo,
>
>Thank you for all that you do...

It is my pleasure in life to do whatever I can to contribute to
the well-being of the worldwide MPE-Image community.


>Would you care to enlighten the list as to the benefits of LFDS vs. Jumbo or vice versa?

I just did, in my previous post ;-)


>Can you point us to a white paper?

Even easier and more convenient for you: I'll read "between the lines"
from my earlier post to hp3000-L, which included some screen shots
of Adager's dialogue:


>This database uses:
>
>  Jumbo datasets (which do not permit dynamic capacity expansion). 

Important difference: Jumbo datasets do NOT permit
                      dynamic capacity expansion (DDX for details,
                      MDX for masters).

                      LargeFile datasets (LFDS) PERMIT DDX/MDX.



>You are running a version of IMAGE that supports LargeFile datasets,
>but this database has Jumbo datasets.
>
>Unfortunately, HP decided not to allow Jumbo datasets to coexist with
>LargeFile datasets.

So, you are forced to choose between Jumbo and LFDS.  This, of course,
is very unfortunate, but I don't believe HP will change its corporate
mind.  I would love to be proven wrong by the good folks at HP.


>Before IMAGE version C.11.00, datasets bigger than 4 GB had to be
>"Jumbo" datasets (with several "chunks", each chunk limited to a
>maximum of 4 GB)...

Jumbo chunks live in Posix and, to "see" them, you must use a command
such as :listfile /TURBO/TEST/JUMBO@, 2

For dataset 5, for instance, you will see SEVERAL different files:
JUMBO05, JUMBO05.001, JUMBO05.002, ...

A LargeFile Dataset (LFDS), on the other hand, is a single file:

>IMAGE version C.11.00 started support for LargeFile DataSets (LFDS),
>which consist of a single MPE/iX file that can be as large as 128 GB.
>
>LargeFile DataSets allow dynamic dataset capacity expansion.

From a practical viewpoint, this is perhaps the most important
attribute of LFDS.  If you have a dataset with more than 4 GB *AND*
if you want to use DDX/MDX, then you should seriously consider
converting it from jumbo to LFDS.


Enjoy,

  _______________
 |               |
 |               |
 |            r  |  Alfredo                  http://www.adager.com                     
 |          e    |                            
 |        g      |  F. Alfredo Rego                   
 |      a        |  Manager, R & D Labs           
 |    d          |  Adager Corporation
 |  A            |  Sun Valley, Idaho 83353-3000            U.S.A.
 |               |
 |_______________|

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