ASM required mirror free space to accommodate disk failures
Blogpost Dutch Prutser January 2 2013 03/01/2013 The summary of the blogpost REQUIRED_MIRROR_FREE _MB is the amount of free space required to restore redundancy after a failure that ASM can tolerate without affecting data availability. This amount depends on the redundancy level and the number of failure groups in the disk group. Normal redundancy disk groups with at least three failure groups require an amount of free space that is equal to the size of a single failure group. Normal redundancy disk groups with only two failure groups require an amount of free space that is equal to the size of a single disk. High redundancy disk groups with at least four failure groups require an amount of free space that is equal to the sum of the size of two failure groups. High redundancy disk groups with only three failure groups require an amount of free space that is equal to the sum of the size of two disks. USABLE_FILE_MB is the amount of disk space available for stor...