ORA-15418: appliance mode not supported for compatible.asm

Posted in: Technical Track

The other day, I was upgrading a compatible.asm parameter to 12.1 on Exadata and I faced this error for the first time :

Indeed, a diskgroup can have this parameter set to TRUE or FALSE :

I then found this note on Metalink : EXADATA : What Is Oracle ASM appliance.mode Attribute (Doc ID 1664261.1) which explains that starting from Exadata, “The Oracle ASM appliance.mode attribute improves disk rebalance completion time  when dropping one or more Oracle ASM disks. This means that redundancy is restored faster after a failure.

Wow, that looks like a pretty cool feature! But it seems that (sadly) we cannot set a 12.1 compatible if this feature is enabled.

Let’s give it a try and deactivate it to set my compatible.asm to 12.1 :

It works ! Now that this compatible.asm is set to 12.1, could we enable that appliance.mode feature again ?

Sadly, no. I hit one of the restrictions; indeed, “The Oracle ASM disk group attribute compatible.asm is set to release, and later. (Appliance mode is not valid with” — then I guess that even of the documentation does not say so, Appliance mode is not valid with a compatible.asm set to either.
Even if it is very weird that Oracle dev “forgot” (?) this cool feature when they released 12c on Exadata, they hopefully “released” it again with I’ll follow up on that when moving this compatible.asm to !

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