ADSM-L

Re: Incremental Backup (full/partial)

2002-08-12 19:23:10
Subject: Re: Incremental Backup (full/partial)
From: Alex Paschal <AlexPaschal AT FREIGHTLINER DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 12 Aug 2002 16:30:18 -0700
Ah, look, Mark, I really hate to do this, because it's making me look like a
horse's hind end for not being graceful about this subject, but just now I
did a...

dsmc inc -incrbydate /

and it updated the Last Backup Completion Date (LID) in a "query filespace
f=d" for the / filespace.  LID doesn't tell you whether you're doing
Partials or Fulls.  The fact of the matter is LID has nothing to do with
Partial backups.

Look, I'm not trying to attack you, I'm not trying to prove you're wrong or
I'm right, and, believe it or not, I'm not trying to nitpick semantics.  I'm
just saying that misleading terminology or terminology used in a misleading
way can mislead those who are new to TSM, haven't taking your class, and are
looking to this mailing list for help and education.  Specifically, in this
case, the thread starter, Ken Horacek, who at this point doesn't know
whether to use the book's terminology or yours to answer the question he has
about what he read in the book.

Alex Paschal
Storage Administrator
Freightliner, LLC
(503) 745-6850 phone/vmail

-----Original Message-----
From: Mark D. Rodriguez [mailto:mark AT MDRCONSULT DOT COM]
Sent: Monday, August 12, 2002 3:16 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Incremental Backup (full/partial)


  Alex,

I have read through your response and I can understand your position.
 However, firat I would like to point out that the TSM documentation is
not always clear and is not always consistant.  The text you quoted from
the Admin Guide is an example of them not being consistant.  Clearly
what they are describing there is a "incremental -incrbydate" type
backup.  And as I stated earlier you can consider it a "partial
incremental", but that does not mean that a "partial incremental is only
acheived by "incremental -incrbydate", that's like saying "I live in
Texas therefore I am a Texan and an American" based on that fact I can
say all Texan's are Americans, but not all Americans are Texans.

I will concede that there is places within the documentation that refers
to the "-incrbydate" option as beeing a "partial backup" and I can show
you IBM/Tivoli education material that describes a partial exactly as I
did in my note.  But rather than nit picking the symantics I would like
to re-phrase my explanation,  Instead of calling it "full incremental"
and "partial incremental" maybe we should use full and non-full.  The
key here is what happens when you don't use "full incrementals", in
particular the Last Incremental Date ( what I refer to as the LID) does
not get updated.  This is a critical peice of information.  Much of the
documentations explanation for other processes are assumming that you
are doing fulls since it keys off of the LID.  In addition, what other
processing is being effected by your "non-full incremental" (filespec
limited or -incrbydate option), i.e. file expiration, rebinding, missed
files etc.

The point that I am really trying to make is you should always be doing
full incremental backups!  The only time to consider anything else is if
there is a severe time constraint on the backup window.

I think this thread has been great.  It has given people a look at how,
what and why TSM is doing what it does.



--
Regards,
Mark D. Rodriguez
President MDR Consulting, Inc.

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