Oracle's Automatic Storage Management (ASM), introduced in Oracle 10g, provides an alternative to raw disk devices for storing Oracle-related files.
Like raw disks, ASM volumes (called diskgroups) have no filesystem and cannot be browsed directly at the operating system level. This makes maintenance a challenge because you cannot use the normal commands to copy and delete files (cp and rm in UNIX, copy and del in Windows).You can use RMAN to back up and restore ASM files and, in 10gR2, you can use ASMCMD to view and manipulate the directory structure. The DBMS_FILE_TRANSFER package in Oracle 10g is yet another way to work with ASM.
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