Very Computer

by **Jame** » Wed, 21 Feb 2001 03:49:09

if i lose some archive logs what can i restore back too?
hypoteticly if i have 20 files and lose 15 file would i only be able to
restore up to the 14 file? how does this work?

by **Uchak** » Wed, 21 Feb 2001 13:48:31

After you start the database from the
most recent hot or cold backup, you
will attempt to recover until a specific time
for example. Oracle will continue to apply the redologs for rolling forward as
long as
you can supply the redo logs.

Please read Rama Velpuri's book
on Oracle Datbase backup and recovery
for an elaborate explanation with specific
examples.

Regards
Willy

by **Niall Litchfiel** » Wed, 21 Feb 2001 18:57:16

You can recover from your last good backup until the first gap in your
archived redo logs. This means

either doing a recover until time, or doing recover until cancel - if you
don't know how many archived logs you actually have.

This is documented in the documentation under the title Incomplete Recovery.
I strongly suggest if you actually need to do this that you read carefully
through this documentation. As Howard Rogers is fond of saying this is
exactly the reason for the introduction for 5 way multiplexing of archived
logs in 8i. A good DBA *should* never lose an archived redo log. (I bet we
all have though <g>).

HTH

--
Niall Litchfield
Oracle DBA
Audit Commission UK

Quote:> if i lose some archive logs what can i restore back too?
> hypoteticly if i have 20 files and lose 15 file would i only be able to
> restore up to the 14 file? how does this work?

by **Jason Seele** » Thu, 22 Feb 2001 04:47:54

Just another question regarding archive logs

If I do a full backup of the database each night, after shutting it down
first. Do I need to keep backups of the archive logs before yesterdays?

If a disaster were to happen during the day, surely the only archive logs
needed would be from today?

Am I correct in my assumtion or am I missing something?

Jason

> You can recover from your last good backup until the first gap in your
> archived redo logs. This means

> either doing a recover until time, or doing recover until cancel - if you
> don't know how many archived logs you actually have.

> This is documented in the documentation under the title Incomplete
Recovery.
> I strongly suggest if you actually need to do this that you read carefully
> through this documentation. As Howard Rogers is fond of saying this is
> exactly the reason for the introduction for 5 way multiplexing of archived
> logs in 8i. A good DBA *should* never lose an archived redo log. (I bet we
> all have though <g>).

> HTH

> --
> Niall Litchfield
> Oracle DBA
> Audit Commission UK

> > if i lose some archive logs what can i restore back too?
> > hypoteticly if i have 20 files and lose 15 file would i only be able to
> > restore up to the 14 file? how does this work?

by **Niall Litchfiel** » Thu, 22 Feb 2001 18:08:49

All things being well you are correct. However this strategy relies on a
single point of failure. Last nights backup. If you don't have the backup,
or you can't restore from it, then you're dead. Being paranoid what we do
for our backup strategy is as follows.

1. Export the entire database every night. - this gives a logical backup for
cases like hardware failure.
2. Backup the database every night
3. Don't delete archives for 4 days.

we also import the export to our DR site daily as well.

--
Niall Litchfield
Oracle DBA
Audit Commission UK

> Just another question regarding archive logs

> If I do a full backup of the database each night, after shutting it down
> first. Do I need to keep backups of the archive logs before yesterdays?

> If a disaster were to happen during the day, surely the only archive logs
> needed would be from today?

> Am I correct in my assumtion or am I missing something?

> Jason

> > You can recover from your last good backup until the first gap in your
> > archived redo logs. This means

> > either doing a recover until time, or doing recover until cancel - if
you
> > don't know how many archived logs you actually have.

> > This is documented in the documentation under the title Incomplete
> Recovery.
> > I strongly suggest if you actually need to do this that you read
carefully
> > through this documentation. As Howard Rogers is fond of saying this is
> > exactly the reason for the introduction for 5 way multiplexing of
archived
> > logs in 8i. A good DBA *should* never lose an archived redo log. (I bet
we
> > all have though <g>).

> > HTH

> > --
> > Niall Litchfield
> > Oracle DBA
> > Audit Commission UK

> > > if i lose some archive logs what can i restore back too?
> > > hypoteticly if i have 20 files and lose 15 file would i only be able
to
> > > restore up to the 14 file? how does this work?

by **Jason Seele** » Fri, 23 Feb 2001 12:04:51

I keep each backup for a week, i.e. one for each day of the week. This also
includes the volume where the archive logs are stored. so at any given point
I have full backups and associated archive logs for the last six days. Also
I have 3 monthly tapes, also full system backups. I have always thought this
would be enough, but then I am new to Oracle so I now have a touch of
paranoia creeping in after your last post 8-).

I like the idea of exporting the database but how long does the export take,
and how big is your database? (rough approximation)

We are running BaaN and it has a lot of tables approx 2500 per system, and
we have three systems in the database (live, test and standard) so all up
there are some 7500 tables. The tablespace holding the data is approx 11Gb
and the one holding the indexes is approx 10Gb.
I have a feeling this could take a long time to export?

Sorry if my questions are annoying and basic, but I'm still waiting for the
"guys with the checkbooks" (finance managers) to approve my Oracle
raining - glad I'm not holding my breath ;-)

Jason

> All things being well you are correct. However this strategy relies on a
> single point of failure. Last nights backup. If you don't have the backup,
> or you can't restore from it, then you're dead. Being paranoid what we do
> for our backup strategy is as follows.

> 1. Export the entire database every night. - this gives a logical backup
for
> cases like hardware failure.
> 2. Backup the database every night
> 3. Don't delete archives for 4 days.

> we also import the export to our DR site daily as well.

> --
> Niall Litchfield
> Oracle DBA
> Audit Commission UK

> > Just another question regarding archive logs

> > If I do a full backup of the database each night, after shutting it down
> > first. Do I need to keep backups of the archive logs before yesterdays?

> > If a disaster were to happen during the day, surely the only archive
logs
> > needed would be from today?

> > Am I correct in my assumtion or am I missing something?

> > Jason

> > > You can recover from your last good backup until the first gap in your
> > > archived redo logs. This means

> > > either doing a recover until time, or doing recover until cancel - if
> you
> > > don't know how many archived logs you actually have.

> > > This is documented in the documentation under the title Incomplete
> > Recovery.
> > > I strongly suggest if you actually need to do this that you read
> carefully
> > > through this documentation. As Howard Rogers is fond of saying this is
> > > exactly the reason for the introduction for 5 way multiplexing of
> archived
> > > logs in 8i. A good DBA *should* never lose an archived redo log. (I
bet
> we
> > > all have though <g>).

> > > HTH

> > > --
> > > Niall Litchfield
> > > Oracle DBA
> > > Audit Commission UK

> > > > if i lose some archive logs what can i restore back too?
> > > > hypoteticly if i have 20 files and lose 15 file would i only be able
> to
> > > > restore up to the 14 file? how does this work?

by **Niall Litchfiel** » Fri, 23 Feb 2001 19:41:52

Answers embedded

Quote:> I keep each backup for a week, i.e. one for each day of the week. This
also
> includes the volume where the archive logs are stored. so at any given
point
> I have full backups and associated archive logs for the last six days.
Also
> I have 3 monthly tapes, also full system backups. I have always thought
this
> would be enough, but then I am new to Oracle so I now have a touch of
> paranoia creeping in after your last post 8-).

Hey paranoia is good for you - how else would I know that they're all out to
get me <g>. I guess what I was getting at is if you actually delete the
archive logs that are older than 1 day (using an os script or whatever) in
order to preserve space, then if last nights backup didn't work or the tape
is unreadable the fact that you have tapes for the previous week is
irrelevant. On our system I have to have three bad tapes before I'm in
trouble.

Quote:
> I like the idea of exporting the database but how long does the export
take,
> and how big is your database? (rough approximation)

We're not as large as you, but a direct export takes somewhere between 30
minutes and an hour to produce a roughly 3.5Gb dump file.This is on a 3 year
old NT box. Of course compressing and then copying this file across a WAN
link for DR takes some time. Suck it and see would be my advice.

Quote:
> Sorry if my questions are annoying and basic, but I'm still waiting for
the
> "guys with the checkbooks" (finance managers) to approve my Oracle
> raining - glad I'm not holding my breath ;-)

Not at all, they are sensible questions from someone who obviously
undertsands the kind of things he needs to consider. Annoying questions are
of the 'What are the default Oracle passwords - I can't be bothered to read
the manual' variety.

As far as the guys with the checkbooks go ask them to consider what the cost
of a days downtime for the entire system is if you have to spend that long
working out how to restore and what data they will have and what if any they
have lost during downtime. Then consider the cost of Oracle training.

--
Niall Litchfield
Oracle DBA
Audit Commission UK

by **Jason Seele** » Sat, 24 Feb 2001 05:20:58

Yes the script deletes logs older than 5 days, so we have abit of redundancy
as each archive log is on 5 different tapes (assuming my maths is correct)

Thanks for your help, I find it is much more informative talking to someone
who is "out there doing it" rather than trolling through some crusty old
manual 8-)

Cheers
Jason

> Answers embedded

> > I keep each backup for a week, i.e. one for each day of the week. This
> also
> > includes the volume where the archive logs are stored. so at any given
> point
> > I have full backups and associated archive logs for the last six days.
> Also
> > I have 3 monthly tapes, also full system backups. I have always thought
> this
> > would be enough, but then I am new to Oracle so I now have a touch of
> > paranoia creeping in after your last post 8-).

> Hey paranoia is good for you - how else would I know that they're all out
to
> get me <g>. I guess what I was getting at is if you actually delete the
> archive logs that are older than 1 day (using an os script or whatever) in
> order to preserve space, then if last nights backup didn't work or the
tape
> is unreadable the fact that you have tapes for the previous week is
> irrelevant. On our system I have to have three bad tapes before I'm in
> trouble.

> > I like the idea of exporting the database but how long does the export
> take,
> > and how big is your database? (rough approximation)

> We're not as large as you, but a direct export takes somewhere between 30
> minutes and an hour to produce a roughly 3.5Gb dump file.This is on a 3
year
> old NT box. Of course compressing and then copying this file across a WAN
> link for DR takes some time. Suck it and see would be my advice.

> > Sorry if my questions are annoying and basic, but I'm still waiting for
> the
> > "guys with the checkbooks" (finance managers) to approve my Oracle
> > raining - glad I'm not holding my breath ;-)

> Not at all, they are sensible questions from someone who obviously
> undertsands the kind of things he needs to consider. Annoying questions
are
> of the 'What are the default Oracle passwords - I can't be bothered to
read
> the manual' variety.

> As far as the guys with the checkbooks go ask them to consider what the
cost
> of a days downtime for the entire system is if you have to spend that long
> working out how to restore and what data they will have and what if any
they
> have lost during downtime. Then consider the cost of Oracle training.

> --
> Niall Litchfield
> Oracle DBA
> Audit Commission UK