Category Archives: Uncategorized

ORA-15095: reached maximum ASM file size (48000 GB) for this disk group

Lately, I’ve stumbled upon this error while trying to create ADVM volume equal 100Tb.

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Duplicate database from RAC to Single node

I bet you know how to duplicate database from primary, or read only standby databases. But do you know how to duplicate from active database RAC environment into Single instance node without ASM or any shared file system? It’s really awkward feeling while searching this simple information, because no one mention about it. While you duplicating database from RAC to the Single, you needs to configure controlfile snapshot to the ASM or shared filesystem. If you haven’t any, you need to create some. Fortunately we’ve got very small ASM diskgroup only for ocr and voting files. So we can involve this group to our process.

rman target sys/pass@RO_standby auxiliary sys/pass@AIM_standby

RMAN> configure snapshot controlfile name to '+ocrvt/hostname';
RMAN> duplicate target database for standby from active database nofilenamecheck;

The duplicate process just using this controlfile snapshot for creating normal controlfile in location which mention in the spfile.

How to convert snapshot standby to primary

In our test environment we are using flashback technology. This technology afford to us to keep our test servers in the actual state regarding to production server, and the same time give the opportunity for testers make their tests for the new features for our system. We can roll back all changes which has made our testers, and roll forward all new changes which has made on primary server without restore whole database. This is very convenient. Couple days ago my colleague asked me if I can convert snapshot standby to primary without roll back changes which has made on this standby. This is important point, because in a normal way if you want to convert snapshot standby  you have to flashback your database, and roll back all changes. But we can escape this.

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ASM Fast Rebalance and ADVM volume.

Good after noon everyone. Today I wanna share you how you can increase rebalance speed for ADVM volume if you didn’t know it yet. Since 11g Oracle has new feature by the name “ASM Fast Rebalance”. All you need to achieve this feature is remount your diskgroup which contain ADVM volume in the restricted mode.

SQL>; alter diskgroup data dismount force;

Diskgroup altered.

SQL>; alter diskgroup data mount restricted;

Diskgroup altered.

This restricted mode prevent any connection from RDBMS and cluster agents for ADVM. And it’s eliminate locks extent map during rebalance operations. In my environment with diskgroup which contain 15Tb ADVM volume, rebalance operation in the normal mount state has took 15 hours for ADVM volume plus 5 hours for database files, and 20 hours in total. When I’ve re-mounted diskgroup in the restricted mode rebalance operation has took 4 hours for ADVM volume plus 3 hours for database files, and 7 hours in total. So as you can see ASM Fast Rebalance has increased my rebalance operations in 3 times.