OCI-15096
lost disk write detected
Cause
A failure either by disk hardware or disk software caused a disk write to to be lost, even though ASM received acknowledgement that the write completed. Alternatively, a clustering hardware failure or a clustering software failure resulted in an ASM instance believing that another ASM instance had crashed, when in fact it was still active.
Action
The disk group is corrupt and cannot be recovered. The disk group must be recreated, and its contents restored from backups.