---
name: "blkmapd"
section: "8"
platform: "linux"
package: "nfs-common"
version: "1:2.8.3-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/blkmapd"
---

# blkmapd(8)

pNFS block layout mapping daemon

## 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 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.

## 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)](/nfs/5.md), [**dmsetup**(8)](/dmsetup/8.md), [**nfs.conf**(5)](/nfs.conf/5.md)

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

## AUTHORS

Haiying Tang \<Tang\_Haiying@emc.com\>\
 Jim Rees \<rees@umich.edu\>