ASM

OOW has been great and I’m reaching the limit of how much information I can consume for a while. I’ll probably spend some weeks or months reading and understanding presentations. Time to go home and practice what I’ve learned. I’m not even going to try to report dutifully on every session today. Just say that I’ve been to Real-World Performance Questions and Answers, Oracle Database Optimizer: Tips for Preventing Suboptimal Execution Plans, Looking Under the Hood at Oracle Clusterware 11g Release 2, and Under the Hood of Oracle Automatic Storage Management: Fault Tolerance. The first one was great fun, 3 of 4 had more than 20 years experience in this field. The youngest “only” 8. Greg Rahn revealed they have a “secret”: they try to solve complex problems with simple solutions. Graham Woods advised people to ask Why? and understand what you are doing before you actually change anything in production. Simple guidelines, but since many are not following them it needs to be repeated. ...

You may get error ORA-32012 if you are on 11g, but have the compatible parameter set to pre-11g in the database you are cloning from, and the spfile for the source database is stored in ASM when you do an RMAN duplicate from active database. To get around this error, I have found two workarounds: Set the value for compatible to at least 11.1 Skip transferring of the spfile during the clone process. Option 1 is a big change for the database (it affects the CBO among other things), but say you need a clone and are going to change this parameter anyway it is the simplest one since you don’t have to create the parameterfile manually. Option 2 means you create the spfile before the cloning starts and remove the clause with spfile from the duplicate command. ...

This is a simple one, a reminder till next time I forget this, since stuff encountered after a Google-search led me astray… Just in case you try to add disks to an existing ASM disk group using syntax like this: alter diskgroup data add disk '/dev/xvdd1' add disk '/dev/xvde1'; You may get error messages like these: ORA-15032: not all alterations performed ORA-15031: disk specification '/dev/xvde1' matches no disks ORA-15025: could not open disk '/dev/xvde1' ORA-15056: additional error message Linux-x86_64 Error: 13: Permission denied Additional information: 42 Additional information: -1614995373 Additional information: 1730318408 ORA-15031: disk specification '/dev/xvdd1' matches no disks ORA-15025: could not open disk '/dev/xvdd1' ORA-15056: additional error message Linux-x86_64 Error: 13: Permission denied Additional information: 42 Additional information: 87328232 Additional information: 8192 Solution: Use the ASM disk names as given when creating them with oracleasm: ...