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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Backups
I didn't say that you would have a problem during OPEN RESETLOGS. A problem
might occur after the OPEN RESETLOGS if you did not grab an immediate "cold"
backup...
If you just open the database to end-users and transactions immediately after the OPEN RESETLOGS, then you have a period when it would be unrecoverable should another media failure or corruption occur before a full backup can be taken. That is, before you can complete a full backup of the database (either "hot" or "cold"), all of the archivelogs generated and saved are *useless*. After all, what good is an archivelog without a valid restored backup to overlay?
That is the reason for the recommendation to get a "cold" backup after an OPEN RESETLOGS; so that you can be absolutely certain that any transaction committed afterwards can be recovered in the event of media failure...
---
There is a certain set of circumstances where the sun, the moon, and the
stars align where you can restore from backups taken *prior* to the OPEN
RESETLOGS and roll forward archivelogs generated after the backup through
the OPEN RESETLOGS to the point-in-time of failure, but the requirements
include:
* database must be version 7.3.3 or higher, so you can save the SCN of
the OPEN RESETLOGS logged to the "alert.log" file
* must have the SCN of the OPEN RESETLOGS available
* the backup taken prior to the resetlogs (used in the restore) must
have been a "hot" backup
* the database instance must not have been shutdown between that "hot"
backup and the events leading to the OPEN RESETLOGS
If any one of these conditions is false, then grabbing a "cold" backup after
an OPEN RESETLOGS is the only way to guarantee that all transactions
committed after the OPEN RESETLOGS can be recovered if media failure occurs
again...
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
Sent: Monday, October 07, 2002 8:13 AM
>
> Tim, et.al,
>
> We use rman on 8.0.6.3 databases. One of our duvelopers was trying to
> delete records from a table and her query deleted everything from the
> table. This caused the application to fail and a point-in_time recovery
was
> nessessary. I was given a time of 11:00AM. I had recovered the database
> until 11:00AM and before opening the database with resetlogs, I asked if
the
> time was correct. After several minutes of discussion with all concerned,
> it was decided that actually we needed to recovery until 9:00AM. I
changed
> the until time in the restore script, restored the database until 9:00AM
and
> recovered it and opened it resetlogs. I had no problem with this.
>
> Ruth
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, October 04, 2002 5:08 PM
>
>
> The one situation where a cold backup can be considered necessary is
> following an OPEN RESETLOGS. If you have a "no data loss" requirement and
> you are in ARCHIVELOG mode, then there is a window following an OPEN
> RESETLOGS where, if the media crashes prior to completing a "hot" backup,
> you could be unrecoverable. File that one under "a bad day"...
>
> It is not a hard-and-fast requirement however, as there is a fairly narrow
> set of circumstances (available since v7.3.3) where it is possible to
> recover using backups and archivelogs generated prior to an OPEN RESETLOGS
> and then continue the roll-forward using archivelogs generated after the
> RESETLOGS, but there several "gotchas" that can mess that up. It would be
a
> gamble to rely on pulling that rabbit out of the hat...
>
> If you ever find yourself entering the command ALTER DATABASE OPEN
RESETLOGS
> on a database that you *really* care about (should be recognized by the
same
> shallow-breathing sweaty-palm symptoms you get when you say, "...now, just
> hand the gun to me, slowly..."), then please get an immediate "cold"
backup
> before opening the database to users. You may have to argue for it, but
be
> sure to leave time for it when folks are asking, "When will the database
be
> back?"
>
> ..other than that situation, there is no advantage of a "cold" backup over
> a "hot" backup; just my $0.02...
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, October 04, 2002 12:33 AM
>
>
> > Cold backup is very good because I don't have to monitor database during
> the
> > cold backup, no objects will run out of space and I can enjoy a peaceful
> time
> > without any chance for my beeper to go off. You must admit that a cold
> backup
> > cannot guarantee you that. Unfortunately, my bosses somehow got the
> curious idea
> > that they have paid big bucks for all those HP 9000 to work and not to
sit
> idle. They
> > even calculated a downtime cost per hour for each critical system and
they
> are extremely
> > reluctant to have them down for extended periods of time (1.1 TB
database
> cannot be
> > backed up in minutes, even with Asymmetrix). That is why they bought me
a
> toy called
> > OPS and why there are policies and procedures about who and how gets
> things in the
> > production database. I would love to do cold backup every day from 8 PM
> until 7 AM and
> > during Sunday football games but it is not very likely that my wish will
> come true.
> > Starlight, starbright, first star I see tonight, I wish I may, I wish I
> might have
> > the wish I wish tonight. That is my best chance to get cold backups
every
> day.
> >
> >
> >
> > On 2002.10.04 01:38 Jared Still wrote:
> > >
> > > OK, Gene, you asked for it. :)
> > >
> > > The context of your message suggests that a hot backup is
> > > somehow more likely to be corrupted than a cold one.
> > >
> > > I hate to resurrect an old flame war, but...
> > >
> > > No, I take it back. I don't hate it a bit. ;)
> > >
> > > There aren't many occasions that call for a cold backup.
> > >
> > > I'm just curious what you believe a cold backup is buying
> > > you that a hot backup won't deliver.
> > >
> > > Jared
> > >
> > > On Thursday 03 October 2002 14:54, Gene Sais wrote:
> > > > wow, never a cold backup for any os,oracle, application upgrades? i
> prefer
> > > > to shutdown everything, backup the filesystems, let the vendor have
> his
> > > > way. if he screws up, its much easier to restore a complete
> filesystem
> > > > than a corrupted database. cold backups are a good thing. i sleep
> good at
> > > > nite :) soon, rman will be another backup method in my toolbox.
but
> when
> > > > that happens, i can see hot backups going away but cold backups will
> still
> > > > be needed on occassion.
> > > >
> > > > >>> rgramolini_at_tax.state.vt.us 10/03/02 04:33PM >>>
> > > >
> > > > I don't do them either, 4.5 years here. Ruth
> > > > ----- Original Message -----
> > > > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > > > Sent: Thursday, October 03, 2002 4:17 PM
> > > >
> > > >
> > > > I haven't done nor recommended a cold backup in 3 years since I've
> been
> > > > using Rman. Just not needed anymore.
> > > >
> > > > Tom Mercadante
> > > > Oracle Certified Professional
> > > >
> > > >
> > > > -----Original Message-----
> > > > Sent: Thursday, October 03, 2002 3:14 PM
> > > > To: Multiple recipients of list ORACLE-L
> > > >
> > > >
> > > > I still prefer cold backups when performing full OS backups.
> > > >
> > > > >>> RROGERS_at_galottery.org 10/03/02 02:28PM >>>
> > > >
> > > > Lest we not forget the archivelogs also during this backup
procedure.
> > > > Ron
> > > >
> > > > >>> rgramolini_at_tax.state.vt.us 10/03/02 01:53PM >>>
> > > >
> > > > I forgot about alter tablespace begin backup; etc. I am spoiled, I
use
> > > > rman
> > > > to do online backups. No problem with recovery!
> > > > Ruth
> > > > ----- Original Message -----
> > > > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > > > Sent: Thursday, October 03, 2002 12:18 PM
> > > >
> > > >
> > > > This doesn't sound right. Put the database in hot backup mode,
> > > > backup (whether using cp to a staging point like the poster here
> > > > is doing or straight to tape using dd or dump or some other
utility),
> > > > come out of hot backup mode. Why wouldn't you be able to recover?
> > > >
> > > > John P Weatherman
> > > > Database Administrator
> > > > Replacements Ltd.
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > Sent: Thursday, October 03, 2002 10:18 AM
> > > > To: Multiple recipients of list ORACLE-L
> > > >
> > > >
> > > > If you want to be able to use any OS backup for restore/recovery
that
> > > > database must be closed when you do the backup. If it is not, you
> > > > won't be
> > > > able to recover.
> > > >
> > > > Just a thot,
> > > > Ruth
> > > >
> > > > ----- Original Message -----
> > > > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > > > Sent: Thursday, October 03, 2002 9:08 AM
> > > >
> > > >
> > > > Robyn,
> > > > We used the DD method on pre 7.1 oracle with RAW devices. It worked
> > > > fine except that it used a lot of tape dumping a raw device when
only
> > > > a
> > > > small portion was used. Using a dd command to place a copy of the
data
> > > > on tape should not be a problem if a restoral is needed. The dd
> > > > function
> > > > is just another OS method of copying data to a tape. I don't know
for
> > > > sure but I think there might be some issues about transportability
of
> > > > the dd tape.
> > > > Other users will know about the transportability issues.
> > > > Ron
> > > > ROR mª¿ªm
> > > >
> > > > >>> Robyn_at_iTeamTech.com 10/02/02 08:08PM >>>
> > > >
> > > > Hello,
> > > >
> > > > I need some info about backups. I am working on a customer site,
and
> > > > have implemented both exports and hot backups. Both jobs copy to a
> > > > separate mount point, and a job scripted by another individual then
> > > > moves the files to tape.
> > > >
> > > > Here's the problem - he's using a dd command, primarily because it
> > > > provides a succinct output he can email to non-technicals. The file
> > > > system is built on a 12 disk A1000 array. We've provided him with a
> > > > ufsdump script, but he's doesn't want to use it. Can the system be
> > > > recovered from this tape? Has anyone ever relied on a dd for a
daily
> > > > backup method? The system is Oracle 9i on Solaris 8.
> > > >
> > > > Robyn
> > > >
> > > > --
> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author: Robyn Anderson Sands
> > > > INET: Robyn_at_iTeamTech.com
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
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> > > > Author: Ron Rogers
> > > > INET: RROGERS_at_galottery.org
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
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> > > > --
> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author: Ruth Gramolini
> > > > INET: rgramolini_at_tax.state.vt.us
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Maili
> > > > ng list and web hosting services
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> ---------------------------------------------------------------------
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> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author: John Weatherman
> > > > INET: john.weatherman_at_replacements.com
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
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> > > > --
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> > > > --
> > > > Author: Ruth Gramolini
> > > > INET: rgramolini_at_tax.state.vt.us
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
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> > > > --
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> > > > --
> > > > Author: Ron Rogers
> > > > INET: RROGERS_at_galottery.org
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
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> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author: Gene Sais
> > > > INET: Gsais_at_co.palm-beach.fl.us
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
> > > > To REMOVE yourself from this mailing list, send an E-Mail message
> > > > to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
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> > > > --
> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author: Mercadante, Thomas F
> > > > INET: NDATFM_at_labor.state.ny.us
> > > >
> > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > > San Diego, California -- Mailing list and web hosting
services
> > >
> ---------------------------------------------------------------------
> > > > To REMOVE yourself from this mailing list, send an E-Mail message
> > > > to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> > > > the message BODY, include a line containing: UNSUB ORACLE-L
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> > > > also send the HELP command for other information (like subscribing).
> > > --
> > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > --
> > > Author: Jared Still
> > > INET: jkstill_at_cybcon.com
> > >
> > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > San Diego, California -- Mailing list and web hosting services
> > > ---------------------------------------------------------------------
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> > >
> >
> > --
> > Mladen Gogala
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Mladen Gogala
> > INET: mgogala_at_adelphia.net
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
> > ---------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
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>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Tim Gorman
> INET: Tim_at_SageLogix.com
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Ruth Gramolini
> INET: rgramolini_at_tax.state.vt.us
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
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> also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Gorman
INET: Tim_at_SageLogix.com
Fat City Network Services -- 858-538-5051 http://www.fatcity.com
San Diego, California -- Mailing list and web hosting services
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Received on Mon Oct 07 2002 - 15:18:50 CDT
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