Re: How the SQL Server World Lives

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/
> >>> > >
> >>> > >
> >>> > >
> >>> > > --