git: xdisk - Link into tree, add manual page

Matthew Dillon dillon at
Sat Oct 30 19:57:03 PDT 2021

commit 28616d01bbfd87b12cbde56b9332d0bc8fec41ec
Author: Matthew Dillon <dillon at>
Date:   Sat Oct 30 19:49:07 2021 -0700

    xdisk - Link into tree, add manual page
    * Link the xdisk driver into the tree and add a quick manual page.
      The xdisk driver uses libdmsg + the hammer2 service daemon to
      implement remote block devices over a network.
      The hammer2 service daemon is the lynchpin of the system, see
      the section on setting up /etc/hammer2 in the hammer2 manual page
      for more information.
    * xdisk works like a dedicated block device, so is NOT like a NFS share.
      At any given time, a particular block device should only be open for
      writing by a single client.  The driver needs some work w/regards to
      maintaining open ref counts and such across the mini-cloud.  Multiple
      clients should not try to share the same block device.
      That said, filesystem performance over xdisk block devices should be
      very good.  Since the filesystem is running on the client-side, system
      buffer cache, read-ahead, and write buffering may be fully employed
      and performance will generally be better than NFS.
    * Note that libdmsg has been in the tree awhile but is still considered
      highly experimental.  It uses encrypted connections but the encryption
      is not considered to be robust at this time.  Authentication is implemented
      via a combination of public/private key pairs and IP addresses.
      The hammer2 manual page describes the directives that may be used to
      create these keys.

Summary of changes:
 share/man/man4/Makefile                    |  1 +
 share/man/man4/{acpi_pvpanic.4 => xdisk.4} | 87 +++++++++++++++++++-----------
 sys/dev/disk/Makefile                      |  1 +
 3 files changed, 59 insertions(+), 30 deletions(-)
 copy share/man/man4/{acpi_pvpanic.4 => xdisk.4} (52%)

DragonFly BSD source repository

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