# phpman > man > blkmapd(8) [blkmapd(8)](https://www.chedong.com/phpMan.php/man/blkmapd/8/markdown) System Manager's Manual [blkmapd(8)](https://www.chedong.com/phpMan.php/man/blkmapd/8/markdown) ## 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 ### -d ### -f ## 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)](https://www.chedong.com/phpMan.php/man/nfs/5/markdown), [**dmsetup**(8)](https://www.chedong.com/phpMan.php/man/dmsetup/8/markdown), [**nfs.conf**(5)](https://www.chedong.com/phpMan.php/man/nfs.conf/5/markdown) RFC 5661 for the NFS version 4.1 specification. RFC 5663 for the pNFS block layout specification. ## AUTHORS Haiying Tang <> Jim Rees <> 11 August 2011 [blkmapd(8)](https://www.chedong.com/phpMan.php/man/blkmapd/8/markdown)