It is important to dismount any active file system configured with an Oracle ADVM volume device file before an Oracle ASM instance is shutdown or a disk group is dismounted. After the file systems are dismounted, all open references to Oracle ASM files are removed and associated disk groups can be dismounted or the instance shut down.
If the Oracle ASM instance or disk group is forcibly shut down or fails while an associated Oracle ACFS is active, the file system is placed into an offline error state. If any file systems are currently mounted on Oracle ADVM volume files, the SHUTDOWN ABORT command should not be used to terminate the Oracle ASM instance without first dismounting those file systems. Otherwise, applications encounter I/O errors and Oracle ACFS user data and metadata being written at the time of the termination may not be flushed to storage before the Oracle ASM storage is fenced. If it is not possible to dismount the file system, then you should run two sync (1) commands to flush cached file system data and metadata to persistent storage before issuing the SHUTDOWN ABORT operation.
Any subsequent attempt to access an offline file system returns an error. Recovering a file system from that state requires dismounting and remounting the Oracle ACFS file system. Dismounting an active file system, even one that is offline, requires stopping all applications using the file system, including any shell references. For example, a previous change directory (cd) into a file system directory. The Linux fuser or lsof commands or Windows handle command list information about processes and open files.
For information about shutting down an Oracle ASM instance, see "About Shutting Down an Oracle ASM Instance". For information about dismounting a disk group, see "Mounting and Dismounting Disk Groups".