ASM: automatic storage management for Oracle

ASM is a feature of Oracle 10g.

ASM simplifies the optimal layout of datafiles, online redo log files, controlfiles and flashback recovery area files.

ASM works with any storage type, be it raw devices or SAN based storage arrays, or NAS.

I/O performance is maximized because files are optimally distributed across the available devices. Whenever a configuration changes (like adding more disks), the distribution is re-balanced (while the database remains online).

ASM maintains redundant copies (that is: mirrors) of the data to protect against data loss. The policy for this reduncy can be configured.