Re: Backup Strategy (NT)

From: Eric D. Pierce <PierceED_at_csus.edu>
Date: Fri, 25 Jan 2002 11:43:09 -0800
Message-ID: <F001.003FB9F1.20020125113017@fatcity.com>

(fwding in case TBC's "cc:" doesn't make it to the list.)

Forwarded message follows ------- Date sent: Fri, 25 Jan 2002 11:12:11 -0800 (PST) 025 To: PierceED_at_csus.edu Copies to: Oracle-l_at_fatcity.com

I gave the right advice for the wrong reasons. My bad. I'll revise the next release of the paper and credit you -- thanks.

Here's the word from Oracle Support:

Doc ID: Note:139327.1

The Differences between Windows NT COPY and Oracle OCOPY When Doing Backups:

When doing an online backup, should you use the Windows NT COPY
command, or the Oracle OCOPY command?

While doing online backups you should use OCOPY, or Oracle7 EBU, or Oracle8 (and later) RMAN. With the OCOPY command you could copy to a backup directory on the hard drive but cannot use OCOPY to copy a file to tape. The other option if you do not want to use ocopy to perform your backup as this does require a lot of disk space is EBU/RMAN that comes with Oracle. Depending on your Oracle version, the distribution includes a utility called EBU (Oracle7) or RMAN (Oracle8 and later) that can be used for online recovery as well. You will need to use a media management product to move the data from RMAN to tape. Legato Storage Manager is provided however there are other products that are supported to be used with this tool.

To backup you will need to use the utility delivered by Oracle, the ocopy command. Utilities like the NT commands copy, xcopy CANNOT be used to back up. The Windows NT feature to be aware of is that NT Backup does not allow files in use to be copied, so you must use the OCOPY utility that Oracle provides to copy the open database files to another disk location. Since OCOPY cannot copy files directly to tape, you will then need to use NT Backup or copy or a similar utility to copy the files to tape, as required.

OCOPY allows writing to continue while the backup is running. The NT COPY is a closed copy and the files may be marked either as "fuzzy" or "corrupt." Ocopy opens the file using CreateFile() with the FILE_SHARE_READ and FILE_SHARE_WRITE flags. This allows writing to continue while we take the backup. Inconsistencies in the backup are repaired by applying archived redo during recovery. The 'copy' command from NT doesn't use these flags since it wants to prevent writes to the file while the copy is taking place.

REFERENCES
[NOTE:41946.1] NT Online Backups
Oracle Backup and Recovery Guide

"Eric D. Pierce" <PierceED_at_csus.edu> wrote:
> fyi:
>
> On 25 Jan 2002 at 1:05, Oracle RDBMS Community Forum
> <ORACLE-L_at_fatcity.com> wrote:
>
>
> >
> > ------------------------------
> >
> > From: "Igor Neyman" <ineyman_at_perceptron.com>
> > Date: Thu, 24 Jan 2002 16:14:25 -0500
> > Subject: Re: Backup Strategy
> >
> > I took a quick look at this paper, and found right away, that it's
> not
> > very accurate, at least in one issue. i.e., it states : < quote>
> The
> > Windows NT command COPY can be used to create a cold backup of a
> database.
> > It cannot be used to make a hot backup. Attempting to perform a hot
> backup
> > with COPY will usually result in an error message being generated
> as the
> > COPY command fails - during a hot backup the database is running
> and thus
> > the database files are locked by the Oracle database process, and
> COPY
> > cannot work on a file that is so locked. < /quote>
> >
> > Wrong. NT 'COPY' has no problems copying 'opened' oracle db files.
> > I'm using it in 'hot backup' scripts on many dozens systems, and it
> works
> > fine.
> >
> > Don't know about the accuracy of the rest of the paper, didn't have
> time
> > to read it all.
> >
> > Igor Neyman, OCP DBA
> > ineyman_at_perceptron.com
> >
> >
> > ----- Original Message -----
> > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > Sent: Thursday, January 24, 2002 7:35 AM
> >
> >
> > > Hi All,
> > >
> > > http://www.geocities.com/tbcox23/
> > >
> > > Go here and get the paper.
> > >
> > > Regards
> > > Venkat
> > > --
> >
>
>

Thomas B. Cox "Saepe in errore sed numquam in dubito" tbcox23@yahoo.com http://www.geocities.com/tbcox23/

"The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary." --H.L. Mencken

End of forwarded message ------- -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Eric D. Pierce INET: PierceED_at_csus.edu

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