Oracle RMAN backups full vs incremental - huge discrepancy in backup speed
Hello,
Our environment: NetBackup 6.0 MP6 on Solaris
We've got a number of Solaris-based SAN media servers that are Oracle servers as well. Each of these servers runs quite a huge (2-12Tb) Oracle database, so that was the main reason to convert them to SAN media servers
.
Althogh we see considerable benefit in backup speed during full backups (up tp 120Mb/s), incremental backups are rather slow (5-10 Mb/s).
Our DBAs say that where is nothing they can do about that. They claim that during incremental backup RMAN scans database files for changed blocks and gives Netbackup only those blocks that are considered to change since last full or incremental backup. How could that be that scanning overhead is so big that it affects backup speed so badly?
Perhaps V$ variables tweaking could improve incremental backup performance.
Comments
block change tracking
There is a parameter called block change tracking - the database remembers the changed block and speeds the incremental backups up.
It's described here: http://www.oracle.com/technology/oramag/oracle/04-... - give this to your dba.
Yes, but that OTN technote
Yes, but that OTN technote works only for Oracle10g. Is there any way to do the same for Oracle 9 instances?
no
You could upgrade the databases, use a disk for the incremental backups or get used to the duration of the incrementals...
It looks like I have plephora
It looks like I have plephora of choices.
Anyway, thanks a lot, Frerk.
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