While I agree with my esteemed colleagues Neil, Christain, Craig, et al, about the need for ensuring proper backups, yada yada, prior to enabling autodefer, you should not be under the impression that detaching the database from the tarnsaction manager leaves it in perilous fragility with respect to its data integrity.
And contrary to earlier statements, network disconnection of an online QUERY session that updates the autodefer-enabled database, does NOT render the database in a non-useable state.
Only a system failure occurring in the midst of a write-enabled open of such a database will cause such a result - and hpe3000 (or even hp3000) system failures are generally quite rare these days.
Or, non-judicious use of PM mode could do the same - although PM could clobber a database even without prior xm detachment.
And, as Kent so clearly demonstrated, there are significant benefits to be realized in specific situations that make sense to detach a database from the xtion manager.
Long-running batch jobs that are run in exclusive open mode against very large databases would be ideal candidates for xm detachment - as long as the risks are known and accounted for.
And, as Neil has stated, the dbcontrol mode 1 is an excellent "programmatic" method of enabling autodefer, the dbutil way would be a more global method of doing it without programming.
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Gilles Schipper
GSA Inc.
HP System Administration Specialists
300 John Street, Box 87651 Thornhill, ON Canada L3T 7R4
Voice: 905.889.3000 Fax: 905.889.3001
email: [log in to unmask] web: http://www.gsainc.com
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---------- Original Message -----------
From: Neil Armstrong <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 2 Feb 2006 15:33:48 -0500
Subject: Re: [HP3000-L] Enable AUTODEFER
> At 02:08 PM 2/2/2006, Dave Powell, MMfab wrote:
> Dear All,
>
> Just as an addition to the great information in this thread this technique
> also speeds up large deletes as well, however, as Christian states I would
> do this only if you have some sort of safety net.(either test db or have a
> backup)
>
> BTW you typically need to open the db exclusively. (mode 3)
>
> Neil
>
> >We have used dbcontrol mode 1 (which I think is equivalent) for about 20
> >years, with no problems, but we use it only in one specific program.
> >
> >Our data base maintenance uses home-grown disk-to-disk versions of dbload /
> >dbunload (similar to the old contrib-library db2disk & disk2db, but in Cobol
> >instead of Fortran). The reload part is WAAAY faster this way.
> >
> >
> >----- Original Message -----
> >From: "Kent Wallace" <[log in to unmask]>
> >To: <[log in to unmask]>
> >Sent: Thursday, February 02, 2006 10:36
> >Subject: [HP3000-L] Enable AUTODEFER
> >
> >
> >Listers:
> >
> >
> >
> >Before I enabled autodefer I loaded 6,367,539 in 154 minutes.
> >
> >
> >
> >After autodefer was enabled I loaded 6,220,800 in 52 minutes.
> >
> >
> >
> >The machine had many other processes running,
> >
> >
> >
> >Kent Wallace
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >* To join/leave the list, search archives, change list settings, *
> >* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
> >
> >* To join/leave the list, search archives, change list settings, *
> >* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
> >
> >
> >
> >--
> >No virus found in this incoming message.
> >Checked by AVG Anti-Virus.
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>
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------- End of Original Message -------
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