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how much recovery area should I temporary allocate in this DG configuration [message #504489] Tue, 26 April 2011 01:39 Go to next message
kytemanaic
Messages: 45
Registered: February 2009
Member
Hi,

currently rdbms version: 10gr2
os: windows 64 bit

Is there any issue with my Datguard solution?

i instance primary
1 instance physical standby
1 recovery catalog which will contains metadata about backups of primary and physical standby.

Let's assume block change frequently, according to http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkscenar001.htm#j1019495

If customer wants recovery windows of 7 days, then

Quote:

If you use a retention policy of a recovery window of X days, and the backup script is executed once each Y days, then if X>=Y, then disk quota is determined by the following formula:

Disk Quota = Size of 1 copy of the database +
size of ((X * ceil(X/Y)) +1) days of archived redo logs





so size of flash recovery area will be as follow

Disk Quota = Size of 1 copy of the database + size of (7+1) days of archive redo logs,

but I understand that from http://download.oracle.com/docs/cd/B19306_01/server.102/b25159/configbp.htm#CHDGCHGE

Quote:

Enable Flashback Database on both the primary and standby database so that the old primary database can be easily reinstated as a new standby database following a failover. If there is a failure during the switchover process, then it can easily be reversed when Flashback Database is enabled.



i.e. flashback database should be included on both primary and physical standby db.

which leads me to another question

from http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/rpfbdb003.htm#BABJJCHF

Quote:

5.3.4.1 Estimating Disk Space Requirements for Flashback Database Logs

The V$FLASHBACK_DATABASE_LOG view can help you estimate how much space to add to your flash recovery area for flashback logs. After you have enabled logging for Flashback Database and set a flashback retention target, allow the database to run under a normal workload for a while, to generate a representative sample of flashback logs. Then run the following query:

SQL> SELECT ESTIMATED_FLASHBACK_SIZE FROM V$FLASHBACK_DATABASE_LOG;


The result is an estimate of the disk space needed to meet the current flashback retention target, based on the database workload since Flashback Database was enabled. Add the amount of disk space specified in $FLASHBACK_DATABASE_LOG.ESTIMATED_FLASHBACK_SIZE to your flash recovery area size, to hold the expected database flashback logs.


in the first place after sizing the flash recovery area for both backups and archive logs, how much size or space should I temporary allocate in flash recovery area in order to allow the database to run under a normal workload for a while and to generate a representative sample of flashback logs. Also how do you define normal work load?

any advice is really appreciated! thanks a lot!
Re: how much recovery area should I temporary allocate in this DG configuration [message #508000 is a reply to message #504489] Wed, 18 May 2011 17:04 Go to previous message
getzeeshan
Messages: 65
Registered: July 2008
Member
The only way you can determine the FRA to be allocated for such operation is by taking an average of archives generated per day and also how much of flashback logs are getting created. Based on this you can use the formula of DB+(7+1) days of archives.

As per my experience with FRA is to have run backup of FRA frequently through RMAN and also take an per day average of Archives being generated.
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