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| Fabrice... |
 Posted: Tue Oct 27, 2009 9:45 am |
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Guest
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Hello
I would like to create a physical standby with Oracle 10g.
2 servers with the same the same structure.
I have read a lot of documentation but I'm always confused about some
points.
I would like to recplicate files from my production server to my standby
server. So, U have created the same directory for :
1. pdump, adump..
2. and all the files : control files, datafile and online redologs.
After cold backup :
- Do I need to copy the backup of the production online redologs to my
standby server. Do the standby could use it ?
Or will they be create automatically by Oracle if one day the standby is
activated ?
- standby redo logs :
It's very hard for me to know what to do with it.
I have understand (i hope) that you need them if we use LGWR instead of ARC.
But my confusion is where to create them : Some articles create standby redo
logs only on the primary .. others on the standby. None on the both.
And sorry I don't undertstand why.
For me, SRL are used by oracle (lgwr/rfs) to write enties directly in it
from primary to standby if we use LGWR mode. So You should create the SRL
on the standby. But I'm not sure. Why some people do the creation on the
primary and not on the standby ?
If we create SRL on the standby, this one should have :
- copy of the cold backup of the online redologs (from primary)
- and n + 1 SRL.
Willo the standby use the copy of the online redo ?
thanks for your help.
fabrice |
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| joel garry... |
| Posted: Tue Oct 27, 2009 3:59 pm |
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Guest
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On Oct 26, 10:45 pm, Fabrice <t... at (no spam) test.com> wrote:
Quote: Hello
I would like to create a physical standby with Oracle 10g.
2 servers with the same the same structure.
I have read a lot of documentation but I'm always confused about some
points.
I would like to recplicate files from my production server to my standby
server. So, U have created the same directory for :
1. pdump, adump..
2. and all the files : control files, datafile and online redologs.
After cold backup :
- Do I need to copy the backup of the production online redologs to my
standby server. Do the standby could use it ?
Or will they be create automatically by Oracle if one day the standby is
activated ?
- standby redo logs :
It's very hard for me to know what to do with it.
I have understand (i hope) that you need them if we use LGWR instead of ARC.
But my confusion is where to create them : Some articles create standby redo
logs only on the primary .. others on the standby. None on the both.
And sorry I don't undertstand why.
For me, SRL are used by oracle (lgwr/rfs) to write enties directly in it
from primary to standby if we use LGWR mode. So You should create the SRL
on the standby. But I'm not sure. Why some people do the creation on the
primary and not on the standby ?
If we create SRL on the standby, this one should have :
- copy of the cold backup of the online redologs (from primary)
- and n + 1 SRL.
Willo the standby use the copy of the online redo ?
thanks for your help.
fabrice
You should pretty much never backup online redologs. The reasoning
is, if you restore online logs over more recent logs, you will lose
data. For cold backups, there is nothing in the redo, since the db
was brought down correctly. If the db was brought down correctly.
Look at the alter database backup controlfile to trace output, note
the resetlog options. (There are obscure exceptions where you want
redologs, but don't even think about it until you understand and have
experience with everything else).
As far as srl's, see http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/dbresource.htm#sthref487
"If you are configuring the maximum protection or maximum availability
level of protection, you must add standby redo log files on all
standby databases. Also, Oracle recommends you add standby redo log
files on the primary database in preparation for a future switchover
or failover. Standby redo log files are required on the primary
database if you want the broker to automatically reinstate the old
(failed) primary database after a fast-start failover."
You should understand that standby databases are merely databases in
constant recovery. So, you should not be afraid of recovery, and
especially be not afraid of hot backups through RMAN. Note that RMAN
doesn't even let you backup redo logs, only archived logs.
jg
--
at (no spam) home.com is bogus.
"Oracle' NSG is hiring all over the US for candidates w/ Oracle's core
and immerging technology." - Oracle recruitment blog. |
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| joel garry... |
| Posted: Tue Oct 27, 2009 5:22 pm |
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Guest
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On Oct 27, 9:10 am, "Fabrice" <emouc... at (no spam) spaminfonietest.fr> wrote:
Quote: Thanks for your answer.
I just want to use the cold backup to create my standby. I prefer do it
manually and understand all the steps.
But, if I don't copy the redologs in my standby from the primary during the
standby creation I will have only standby redologs. If later, I realize a
switchover (so my standby is the primary) what redologs Oracle are going to
use ?
Not the standby redologs because they are use only for the standby role. Are
the online redologs in the standby (primary now) going to be created from
scratch by oracle If I realize a switchover ?
Thnaks fabrice.
It's been a while since I've done it, but IIRC Oracle creates them
when you activate the standby controlfile. I hesitate to say anything
though, because I don't know all the modern variants, I don't trust my
memory, and I went away from cold backups for this kind of thing long
ago.
I applaud you wanting to understand the steps. I'd say, try it and
see what errors you hit. You might also consider using Oracle's
recommended way and watch things very carefully.
How Recovery Manager Duplicates a Database (note "for standby"
differences): http://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/rcmdupdb.htm#sthref908
There used to be a white paper about switching over and switching
back, but it was kind of complicated and now is handled more sanely by
the modern Oracle.
jg
--
at (no spam) home.com is bogus.
"I'm not dead yet!" http://www.pcpro.co.uk/news/352807/facebook-to-preserve-accounts-of-the-dead |
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| Mladen Gogala... |
| Posted: Tue Oct 27, 2009 6:49 pm |
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Guest
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On Tue, 27 Oct 2009 06:45:52 +0100, Fabrice wrote:
Quote: Hello
I would like to create a physical standby with Oracle 10g. 2 servers
with the same the same structure.
What seems to be the problem?
Quote:
I have read a lot of documentation but I'm always confused about some
points.
I would like to recplicate files from my production server to my standby
server. So, U have created the same directory for :
1. pdump, adump..
2. and all the files : control files, datafile and online redologs.
After cold backup :
- Do I need to copy the backup of the production online redologs to my
standby server. Do the standby could use it ? Or will they be create
automatically by Oracle if one day the standby is activated ?
- standby redo logs :
It's very hard for me to know what to do with it. I have understand (i
hope) that you need them if we use LGWR instead of ARC. But my confusion
is where to create them : Some articles create standby redo logs only on
the primary .. others on the standby. None on the both. And sorry I
don't undertstand why.
For me, SRL are used by oracle (lgwr/rfs) to write enties directly in it
from primary to standby if we use LGWR mode. So You should create the
SRL on the standby. But I'm not sure. Why some people do the creation
on the primary and not on the standby ?
If we create SRL on the standby, this one should have : - copy of the
cold backup of the online redologs (from primary) - and n + 1 SRL.
Willo the standby use the copy of the online redo ?
thanks for your help.
fabrice
Everything is described here:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/toc.htm
The book is actually a step by step recipe how to create a standby db.
There also other helpful sources, like this:
http://www.oracle.com/technology/deploy/availability/pdf/
MAA_WP_10g_RACPrimarySingleInstancePhysicalStandby.pdf
If you are unwilling to read the literature, please subscribe to
oracle-l at (no spam) freelists.org, they will gladly answer all of your questions,
this is not the right forum.
--
http://mgogala.freehostia.com |
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| Fabrice... |
| Posted: Tue Oct 27, 2009 8:10 pm |
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Guest
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"joel garry" <joel-garry at (no spam) home.com> a écrit dans le message de news:
bacdc7c4-a8c6-4342-8a92-6232394cd3d6 at (no spam) u16g2000pru.googlegroups.com...
On Oct 26, 10:45 pm, Fabrice <t... at (no spam) test.com> wrote:
Quote: Hello
I would like to create a physical standby with Oracle 10g.
2 servers with the same the same structure.
I have read a lot of documentation but I'm always confused about some
points.
I would like to recplicate files from my production server to my standby
server. So, U have created the same directory for :
1. pdump, adump..
2. and all the files : control files, datafile and online redologs.
After cold backup :
- Do I need to copy the backup of the production online redologs to my
standby server. Do the standby could use it ?
Or will they be create automatically by Oracle if one day the standby is
activated ?
- standby redo logs :
It's very hard for me to know what to do with it.
I have understand (i hope) that you need them if we use LGWR instead of
ARC.
But my confusion is where to create them : Some articles create standby
redo
logs only on the primary .. others on the standby. None on the both.
And sorry I don't undertstand why.
For me, SRL are used by oracle (lgwr/rfs) to write enties directly in it
from primary to standby if we use LGWR mode. So You should create the SRL
on the standby. But I'm not sure. Why some people do the creation on the
primary and not on the standby ?
If we create SRL on the standby, this one should have :
- copy of the cold backup of the online redologs (from primary)
- and n + 1 SRL.
Willo the standby use the copy of the online redo ?
thanks for your help.
fabrice
You should pretty much never backup online redologs. The reasoning
is, if you restore online logs over more recent logs, you will lose
data. For cold backups, there is nothing in the redo, since the db
was brought down correctly. If the db was brought down correctly.
Look at the alter database backup controlfile to trace output, note
the resetlog options. (There are obscure exceptions where you want
redologs, but don't even think about it until you understand and have
experience with everything else).
As far as srl's, see
http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/dbresource.htm#sthref487
"If you are configuring the maximum protection or maximum availability
level of protection, you must add standby redo log files on all
standby databases. Also, Oracle recommends you add standby redo log
files on the primary database in preparation for a future switchover
or failover. Standby redo log files are required on the primary
database if you want the broker to automatically reinstate the old
(failed) primary database after a fast-start failover."
You should understand that standby databases are merely databases in
constant recovery. So, you should not be afraid of recovery, and
especially be not afraid of hot backups through RMAN. Note that RMAN
doesn't even let you backup redo logs, only archived logs.
jg
--
at (no spam) home.com is bogus.
"Oracle' NSG is hiring all over the US for candidates w/ Oracle's core
and immerging technology." - Oracle recruitment blog.
Thanks for your answer.
I just want to use the cold backup to create my standby. I prefer do it
manually and understand all the steps.
But, if I don't copy the redologs in my standby from the primary during the
standby creation I will have only standby redologs. If later, I realize a
switchover (so my standby is the primary) what redologs Oracle are going to
use ?
Not the standby redologs because they are use only for the standby role. Are
the online redologs in the standby (primary now) going to be created from
scratch by oracle If I realize a switchover ?
Thnaks fabrice. |
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