什么是" ASM file metadata operation "等待事件? 这是一个内部的undocumented等待事件： "ASM file metadata operation" event is associated with database (instance) communication with ASM (instance). If the database has files in ASM disk group(s) it needs to access disk group(s), get extent maps for files that it already has, get updated extent info (e.g. after a rebalance), create new files in ASM etc. High waits for 'ksv master wait' while doing an ASM file metadata operation were reported when a data migration utility was running. This wait was also seen for a drop of a tablespace. Many waits for "ASM metadata file operation" may be seen under kfnConnect when sessions query ASM group statistics in a DB instance. Rediscovery Notes: Waits occur under repeated kfnConnect calls when querying certain views based on fixed (X$) views, such as V$ASM_DISKGROUP_STAT. At this time on the ASM only a few process(one or two) will be on non-idle wait events such as "ASM file metadata operation" . WAITING FOR 'ASM FILE METADATA OPERATION' DURING RMAN BACKUP & ASM HANGS
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1278068
