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



NAME
       blkmapd - pNFS block layout mapping daemon

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

DESCRIPTION
       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  vol‐
       umes.   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  con‐
       struct logical devices that reflect the server topology, and passes these devices to the ker‐
       nel for use by the pNFS block layout client.

OPTIONS
       -h     Display usage message.

       -d     Performs device discovery only then exits.

       -f     Runs blkmapd in the foreground and sends output to stderr (as opposed to syslogd)

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

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

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

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

AUTHORS
       Haiying Tang <Tang_Haiying AT emc.com>
       Jim Rees <rees AT umich.edu>



                                           11 August 2011                                 blkmapd(8)