Re: How the SQL Server World Lives

[Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>]

It can because the save is operating on both the object header and the 
data portion of the object.  In the cases I have run into either the 
save was canceled manually with an *IMMED option, or save while active 
checkpoints were in limbo, and a couple of cases were the object was 
locked.    Remember a save is more than just reading the data portion of 
the object, it updates the object header and other internal structures 
while it's operating.

All of the errors I have encountered have been on data objects (tables, 
indexes, etc)   I have yet to see it on V7, rarely on V6, and often 
enough on V5R4 to be concerning.

Jim Oberholtzer
Chief Technical Architect
Agile Technology Architects


On 1/29/2013 4:16 PM, Glenn Gundermann wrote:
> I understood it that a save could detect a corrupt file, not that it would be the one corrupting it.
>
> Glenn
>
> -----Original Message-----
> From: Charles Wilt<charles.wilt@xxxxxxxxx>
> Sender:midrange-l-bounces@xxxxxxxxxxxx
> Date: Tue, 29 Jan 2013 17:12:43
> To: Midrange Systems Technical Discussion<midrange-l@xxxxxxxxxxxx>
> Reply-To: Midrange Systems Technical Discussion<midrange-l@xxxxxxxxxxxx>
> Subject: Re: How the SQL Server World Lives
>
> Jim,
>
> I'm a bit surprised at that...I'd expect a SAVE operation to be 99.9% read
> only.  I don't see how a read operation could corrupt an object.
>
> Save-while-active, maybe...
>
> Anybody, looking at you Chuck;)  , know the details?
>
> Charles
>
>
> On Tue, Jan 29, 2013 at 5:01 PM, Jim Oberholtzer<
> midrangel@xxxxxxxxxxxxxxxxx>  wrote:
>
> > >  To the contrary; Save operations that are killed in the middle, or fail
> > >  for a multitude of reasons will cause a damaged object.  I've probably
> > >  called in 15  - 20 PMRs over the years and had one critsit over that
> > >  very topic.   The critsit was while I was VP IT and we were down for
> > >  several days.  It happened while I as at COMMON in Nashville, I remember
> > >  it vividly.  Ask Larry what my mood was like that week!  The only thing
> > >  that made that week worse was Al Barsa passing.
> > >
> > >  You are correct that a damaged object will not be saved properly, but a
> > >  save operation that fails/or is killed (end immediate)  can cause a
> > >  damaged object as well.
> > >
> > >  Jim Oberholtzer
> > >  Chief Technical Architect
> > >  Agile Technology Architects
> > >
> > >
> > >  On 1/29/2013 3:49 PM, Charles Wilt wrote:
> > > >  >  Jim,
> > > >  >
> > > >  >  I think you've got it backward...
> > > >  >
> > > >  >  I don't believe it even possible for a SAVE to damage an object.  But a
> > > >  >  damaged object is often detected during the SAVE operation.
> > > >  >
> > > >  >  Charles
> > > >  >
> > > >  >
> > > >  >  On Tue, Jan 29, 2013 at 4:45 PM, Jim Oberholtzer<
> > > >  >  midrangel@xxxxxxxxxxxxxxxxx>   wrote:
> > > >  >
> > > > > >  >>  >    The question of if a damaged object is considered a corrupted file
> > >  then
> > > > > >  >>  >    yes, I have seen it.  Usually it's as the result of a Save/Restore
> > > > > >  >>  >    operation that failed, but it does happen.
> > > > > >  >>  >
> > > > > >  >>  >    Jim Oberholtzer
> > > > > >  >>  >    Chief Technical Architect
> > > > > >  >>  >    Agile Technology Architects
> > > > > >  >>  >
> > > > > >  >>  >
> > > > > >  >>  >    On 1/29/2013 3:02 PM, Roger Harman wrote:
> > > > > > >  >>>  >    >   A recent article, "My SQL Server Database is Corrupt - Now
> > >  What?!", had
> > > > > >  >>  >    some
> > > > > > >  >>>  >    >   interesting statements from the author:
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   .         I was asked how often corruption really occurs in the
> > >  real
> > > > > >  >>  >    world.
> > > > > > >  >>>  >    >   My answer was, "hundreds to thousands of times every week across
> > >  the
> > > > > >  >>  >    world,
> > > > > > >  >>>  >    >   in the tens of millions of SQL Server databases.".
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   .         Every single week I receive multiple emails asking for
> > >  some
> > > > > >  >>  >    advice
> > > > > > >  >>>  >    >   about corruption recovery. When I'm teaching about corruption in
> > >  our High
> > > > > > >  >>>  >    >   Availability and Disaster Recovery Immersion Event, I always
> > >  tell the
> > > > > >  >>  >    class
> > > > > > >  >>>  >    >   that I expect every DBA to see database corruption at some point
> > >  during
> > > > > > >  >>>  >    >   their career.
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   .         I'll end by saying this: if you think that corruption
> > >  won't
> > > > > >  >>  >    happen
> > > > > > >  >>>  >    >   to you at some point in your career, I think you'll be
> > >  surprised. Be
> > > > > > >  >>>  >    >   prepared!
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   I'm curious..  How many of you have seen corruption on our
> > >  platform?  In
> > > > > >  >>  >    25+
> > > > > > >  >>>  >    >   years on S/38, AS/400, and IBM-i, I have NEVER had an issue with
> > >  corrupt
> > > > > > >  >>>  >    >   files/tables.  In 1 year of SQL Server at my former employer, I
> > >  saw it
> > > > > > >  >>>  >    >   happen at least 3 times.  I was shocked but the Microsoft bigots
> > >  in the
> > > > > > >  >>>  >    >   company just shook it off as status quo.
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   Here's the article but you have to be a member to read it.
> > > > > > >  >>>  >    >   http://www.sqlservercentral.com/articles/Corruption/96117/
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >
> > > > > > >  >>>  >    >   --