NFS version 4 servers must be able to recover without data loss from multiple power failures (including cascading power failures, that is, several power failures in quick succession), operating system failures, and hardware failure of components other than the storage medium itself (for example, disk, nonvolatile RAM).

• NFS version 4 servers must be able to recover without data loss from multiple power failures (including cascading power failures, that is, several power failures in quick succession), operating system failures, and hardware failure of components other than the storage medium itself (for example, disk, nonvolatile RAM).

• Some examples of stable storage that are allowable for an NFS server include:

• • Media commit of data, that is, the modified data has been successfully written to the disk media, for example, the disk platter.
  • An immediate reply disk drive with battery-backed on- drive intermediate storage or uninterruptible power system (UPS).
  • Server commit of data with battery-backed intermediate storage and recovery software.
  • Cache commit with uninterruptible power system (UPS) and recovery software.