Caution: This version of this document is no longer maintained. For the latest documentation, see

Shared object that supports the Power-Safe filesystem (QNX Neutrino)


driver ... qnx6 qnx6_options... &

Runs on:



Control which users (if any) can suspend the taking of snapshots (via a flag in the DCMD_FSYS_FILEFLAGS devctl() command). The default is root.
Enable a block overallocation heuristic for small file writes.
Set the frequency of automatic snapshots; the default is 10 seconds. A filesystem snapshot is explicitly made when you call sync() or fsync(), or from this periodic timer.
Specify the required disk synchronization capability. The mode mode must be one of the following:

Note: If the drive doesn't support synchronizing, can't guarantee that the filesystem is power-safe. You can use the sync option to override this requirement at your own risk.


The shared object provides support for Power-Safe (copy-on-write/snapshot) filesystems. It's automatically loaded by the devb-* drivers when mounting a Power-Safe filesystem.

See also:

chkqnx6fs, devb-*, mkqnx6fs

"Power-Safe filesystem" in the Filesystems chapter of the System Architecture guide

"Power-Safe filesystem" in the Filesystems chapter of the Neutrino User's Guide