55b247843a
gmultipath.8: Add HISTORY Adjust sentences with bad phrases picked up by igor ggatec.8: Add HISTORY ggated.8: Add HISTORY ggatel.8: Add HISTORY Seperate out sentence as advised by igor. hastctl.8: Add HISTORY hastd.8: Add HISTORY Fix sentence highlighted by igor. iscontrol.8: Add HISTORY mdmfs.8: Add HISTORY Address issues raised by igor mount_nfs.8: Add HISTORY Not sure where mount_nfs first showed up, but the verison used in the BSD's originates from 4.4BSD according to CSRG archive. Though commercial offerings from Sun and others covers older systems, eg https://groups.google.com/forum/#!topic/net.unix-wizards/lMe7aQikqJI nandfs.8: Add HISTORY Adjust sentence in description to address bad phrase highlighted by igor. nvmecontrol.8: Add HISTORY PR: 212491 PR: 212498 PR: 212499 PR: 212500 PR: 212501 PR: 212502 PR: 212505 PR: 212508 PR: 212540 PR: 212543 PR: 212546 Submitted by: Sevan Janiyan <venture37@geeklan.co.uk>
238 lines
6.6 KiB
Groff
238 lines
6.6 KiB
Groff
.\" Copyright (c) 2010 The FreeBSD Foundation
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This software was developed by Pawel Jakub Dawidek under sponsorship from
|
|
.\" the FreeBSD Foundation.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 8, 2016
|
|
.Dt HASTD 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm hastd
|
|
.Nd "Highly Available Storage daemon"
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Fl dFh
|
|
.Op Fl c Ar config
|
|
.Op Fl P Ar pidfile
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
daemon is responsible for managing highly available GEOM providers.
|
|
.Pp
|
|
.Nm
|
|
allows the transpaent storage of data on two physically separated machines
|
|
connected over a TCP/IP network.
|
|
Only one machine (cluster node) can actively use storage provided by
|
|
.Nm .
|
|
This machine is called primary.
|
|
The
|
|
.Nm
|
|
daemon operates on block level, which makes it transparent to file
|
|
systems and applications.
|
|
.Pp
|
|
There is one main
|
|
.Nm
|
|
daemon which starts new worker process as soon as a role for the given
|
|
resource is changed to primary or as soon as a role for the given
|
|
resource is changed to secondary and remote (primary) node will
|
|
successfully connect to it.
|
|
Every worker process gets a new process title (see
|
|
.Xr setproctitle 3 ) ,
|
|
which describes its role and resource it controls.
|
|
The exact format is:
|
|
.Bd -literal -offset indent
|
|
hastd: <resource name> (<role>)
|
|
.Ed
|
|
.Pp
|
|
If (and only if)
|
|
.Nm
|
|
operates in primary role for the given resource, a corresponding
|
|
.Pa /dev/hast/<name>
|
|
disk-like device (GEOM provider) is created.
|
|
File systems and applications can use this provider to send I/O
|
|
requests to.
|
|
Every write, delete and flush operation
|
|
.Dv ( BIO_WRITE , BIO_DELETE , BIO_FLUSH )
|
|
is sent to the local component and replicated on the remote (secondary) node
|
|
if it is available.
|
|
Read operations
|
|
.Dv ( BIO_READ )
|
|
are handled locally unless an I/O error occurs or the local version of the data
|
|
is not up-to-date yet (synchronization is in progress).
|
|
.Pp
|
|
The
|
|
.Nm
|
|
daemon uses the GEOM Gate class to receive I/O requests from the
|
|
in-kernel GEOM infrastructure.
|
|
The
|
|
.Nm geom_gate.ko
|
|
module is loaded automatically if the kernel was not compiled with the
|
|
following option:
|
|
.Bd -ragged -offset indent
|
|
.Cd "options GEOM_GATE"
|
|
.Ed
|
|
.Pp
|
|
The connection between two
|
|
.Nm
|
|
daemons is always initiated from the one running as primary to the one
|
|
running as secondary.
|
|
When the primary
|
|
.Nm
|
|
is unable to connect or the connection fails, it will try to re-establish
|
|
the connection every few seconds.
|
|
Once the connection is established, the primary
|
|
.Nm
|
|
will synchronize every extent that was modified during connection outage
|
|
to the secondary
|
|
.Nm .
|
|
.Pp
|
|
It is possible that in the case of a connection outage between the nodes the
|
|
.Nm
|
|
primary role for the given resource will be configured on both nodes.
|
|
This in turn leads to incompatible data modifications.
|
|
Such a condition is called a split-brain and cannot be automatically
|
|
resolved by the
|
|
.Nm
|
|
daemon as this will lead most likely to data corruption or loss of
|
|
important changes.
|
|
Even though it cannot be fixed by
|
|
.Nm
|
|
itself, it will be detected and a further connection between independently
|
|
modified nodes will not be possible.
|
|
Once this situation is manually resolved by an administrator, the resource
|
|
on one of the nodes can be initialized (erasing local data), which makes
|
|
a connection to the remote node possible again.
|
|
Connection of the freshly initialized component will trigger full resource
|
|
synchronization.
|
|
.Pp
|
|
A
|
|
.Nm
|
|
daemon never picks its role automatically.
|
|
The role has to be configured with the
|
|
.Xr hastctl 8
|
|
control utility by additional software like
|
|
.Nm ucarp
|
|
or
|
|
.Nm heartbeat
|
|
that can reliably manage role separation and switch secondary node to
|
|
primary role in case of the primary's failure.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
daemon can be started with the following command line arguments:
|
|
.Bl -tag -width ".Fl P Ar pidfile"
|
|
.It Fl c Ar config
|
|
Specify alternative location of the configuration file.
|
|
The default location is
|
|
.Pa /etc/hast.conf .
|
|
.It Fl d
|
|
Print or log debugging information.
|
|
This option can be specified multiple times to raise the verbosity
|
|
level.
|
|
.It Fl F
|
|
Start the
|
|
.Nm
|
|
daemon in the foreground.
|
|
By default
|
|
.Nm
|
|
starts in the background.
|
|
.It Fl h
|
|
Print the
|
|
.Nm
|
|
usage message.
|
|
.It Fl P Ar pidfile
|
|
Specify alternative location of a file where main process PID will be
|
|
stored.
|
|
The default location is
|
|
.Pa /var/run/hastd.pid .
|
|
.El
|
|
.Sh FILES
|
|
.Bl -tag -width ".Pa /var/run/hastd.pid" -compact
|
|
.It Pa /etc/hast.conf
|
|
The configuration file for
|
|
.Nm
|
|
and
|
|
.Xr hastctl 8 .
|
|
.It Pa /var/run/hastctl
|
|
Control socket used by the
|
|
.Xr hastctl 8
|
|
control utility to communicate with
|
|
.Nm .
|
|
.It Pa /var/run/hastd.pid
|
|
The default location of the
|
|
.Nm
|
|
PID file.
|
|
.El
|
|
.Sh EXIT STATUS
|
|
Exit status is 0 on success, or one of the values described in
|
|
.Xr sysexits 3
|
|
on failure.
|
|
.Sh EXAMPLES
|
|
Launch
|
|
.Nm
|
|
on both nodes.
|
|
Set role for resource
|
|
.Nm shared
|
|
to primary on
|
|
.Nm nodeA
|
|
and to secondary on
|
|
.Nm nodeB .
|
|
Create file system on
|
|
.Pa /dev/hast/shared
|
|
provider and mount it.
|
|
.Bd -literal -offset indent
|
|
nodeB# hastd
|
|
nodeB# hastctl role secondary shared
|
|
|
|
nodeA# hastd
|
|
nodeA# hastctl role primary shared
|
|
nodeA# newfs -U /dev/hast/shared
|
|
nodeA# mount -o noatime /dev/hast/shared /shared
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr sysexits 3 ,
|
|
.Xr geom 4 ,
|
|
.Xr hast.conf 5 ,
|
|
.Xr ggatec 8 ,
|
|
.Xr ggated 8 ,
|
|
.Xr ggatel 8 ,
|
|
.Xr hastctl 8 ,
|
|
.Xr mount 8 ,
|
|
.Xr newfs 8 ,
|
|
.Xr g_bio 9
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility appeared in
|
|
.Fx 8.1 .
|
|
.Sh AUTHORS
|
|
The
|
|
.Nm
|
|
was developed by
|
|
.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org
|
|
under sponsorship of the FreeBSD Foundation.
|