blkmapd(8) System Manager's Manual blkmapd(8)

blkmapd - pNFS block layout mapping daemon

blkmapd [-h] [-d] [-f]

The blkmapd daemon performs device discovery and mapping for the parallel NFS (pNFS) block layout client [RFC5663].

The pNFS block layout protocol builds a complex storage hierarchy from a set of simple volumes. These simple volumes are addressed by content, using a signature on the volume to uniquely name each one. The daemon locates a volume by examining each block device in the system for the given signature.

The topology typically consists of a hierarchy of volumes built by striping, slicing, and concatenating the simple volumes. The blkmapd daemon uses the device-mapper driver to construct logical devices that reflect the server topology, and passes these devices to the kernel for use by the pNFS block layout client.

Display usage message.
Performs device discovery only then exits.
Runs blkmapd in the foreground and sends output to stderr (as opposed to syslogd)

The blkmapd daemon recognizes the following value from the [general] section of the /etc/nfs.conf configuration file:

Tells blkmapd where to look for the rpc_pipefs filesystem. The default value is /var/lib/nfs/rpc_pipefs.

nfs(5), dmsetup(8), nfs.conf(5)

RFC 5661 for the NFS version 4.1 specification.
RFC 5663 for the pNFS block layout specification.

Haiying Tang <>
Jim Rees <>

11 August 2011