mirror_zfs/man/man8/zgenhostid.8
Olaf Faaland b9373170e3 Add zgenhostid utility script
Turning the multihost property on requires that a hostid be set to allow
ZFS to determine when a foreign system is attemping to import a pool.
The error message instructing the user to set a hostid refers to
genhostid(1).

Genhostid(1) is not available on SUSE Linux.  This commit adds a script
modeled after genhostid(1) for those users.

Zgenhostid checks for an /etc/hostid file; if it does not exist, it
creates one and stores a value.  If the user has provided a hostid as an
argument, that value is used.  Otherwise, a random hostid is generated
and stored.

This differs from the CENTOS 6/7 versions of genhostid, which overwrite
the /etc/hostid file even though their manpages state otherwise.

A man page for zgenhostid is added. The one for genhostid is in (1), but
I put zgenhostid in (8) because I believe it's more appropriate.

The mmp tests are modified to use zgenhostid to set the hostid instead
of using the spl_hostid module parameter.  zgenhostid will not replace
an existing /etc/hostid file, so new mmp_clear_hostid calls are
required.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes #6358
Closes #6379
2017-07-25 13:22:03 -04:00

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2.0 KiB
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.\" Copyright (c) 2017 by Lawrence Livermore National Security, LLC.
.\"
.Dd July 24, 2017
.Dt ZGENHOSTID 8 SMM
.Os Linux
.Sh NAME
.Nm zgenhostid
.Nd generate and store a hostid in
.Em /etc/hostid
.Sh SYNOPSIS
.Nm
.Op Ar hostid
.Sh DESCRIPTION
If
.Em /etc/hostid
does not exist, create it and store a hostid in it. If the user provides
.Op Ar hostid
on the command line, store that value. Otherwise, randomly generate a
value to store.
.Pp
This emulates the
.Xr genhostid 1
utility and is provided for use on systems which do not include the utility.
.Pp
.Sh OPTIONS
.Op Ar hostid
Specifies the value to be placed in
.Em /etc/hostid .
It must be a number with a value between 1 and 2^32-1. This value
.Sy must
be unique among your systems. It must be expressed in hexadecimal and be
exactly 8 digits long.
.Sh EXAMPLES
.Bl -tag -width Ds
.It Generate a random hostid and store it
.Bd -literal
# zgenhostid
.Ed
.It Record the libc-generated hostid in Em /etc/hostid
.Bd -literal
# zgenhostid $(hostid)
.Ed
.It Record a custom hostid (0xdeadbeef) in Em etc/hostid
.Bd -literal
# zgenhostid deadbeef
.Ed
.El
.Sh SEE ALSO
.Xr spl-module-parameters 5 ,
.Xr genhostid 1 ,
.Xr hostid 1