Wednesday, June 29, 2011


A colleague of mine recently brought to my attention a curious wait event that they were experiencing for 'ASM file metadata operation' which occurs when doing operations such as a DROP TABLESPACE, or in this case when using Data Pump. Though the server was basically not doing anything the CPU usage was 100% and there was the strange wait event on 'ASM file metadata operation' with high waits on 'ksv master wait'. So to Oracle Support they went via opening an SR.

It seems that upon applying a PSU to (as of this writing PSU 2 is that latest so likely this will not occur in PSU 3 but that is only my guess) the parameter cell_offload_processing is set to TRUE. In an Exadata environment this is the appropriate setting, however, in a non-Exadata environment, which it was in this case, this causes performance issues to arise as processes on the RDBMS side await on a reply from the ASM side which is trying to delivery smart-scan results.

The quick fix is of course to simply reset the parameter to FALSE, i.e. 'ALTER SYSTEM SET cell_offload_processing = FALSE'. If you prefer you can instead apply patch 11800170. Per the MOS note, "High 'ksv master wait' And 'ASM File Metadata Operation' Waits In Non-Exadata 11g [ID 1308282.1]" this issue is fixed in and 12.1.

Of course is the likely next patch set which is not yet released but is likely in testing. I've been seeing this 12.1 designation on MOS recently which is a good indication that this is the next version for the database, which is likely in early testing. I think that is an entry for a good blog, namely what features I'd like to see in the next database release, and what is likely to be included by Oracle. Attending OpenWorld 2011 would certainly help with that posting, come on Oracle, where is my Blogger approval ;-).