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mirror of https://git.FreeBSD.org/ports.git synced 2024-11-23 00:43:28 +00:00
freebsd-ports/sysutils/diskcheckd/files/diskcheckd.8
Chris Rees 05848572c0 - Some bugfixes:
* Calculate delays in microseconds, so that delays of less than
   one second between reads (needed to implement rates exceeding
   64KB/sec) do not get rounded down to zero.

 * Fix a reinitialization problem when handling SIGHUP.

 * Additional debug messages (only with -d).

 * Comment and manpage improvememts

- Pass maintainership to submitter

PR:		ports/115853 ports/143566
Submitted by:	perryh@pluto.rain.com
2011-08-31 11:40:26 +00:00

208 lines
6.0 KiB
Groff

.\" Copyright (c) 2000, 2001 Ben Smithurst <ben@FreeBSD.org>
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" $FreeBSD$
.\"
.Dd July 4, 2001
.Dt DISKCHECKD 8
.Os
.Sh NAME
.Nm diskcheckd
.Nd daemon to check for disk read errors
.Sh SYNOPSIS
.Nm
.Op Fl d
.Op Fl f Ar conf_file
.Op Fl o Ar save_file
.Sh DESCRIPTION
.Nm
is a daemon which runs in the background,
reading entire disks to find any read errors on those disks.
The disks which should be scanned,
and the rates at which they should be scanned,
must be specified in the configuration file,
which is
.Pa /usr/local/etc/diskcheckd.conf
by default.
.Pp
Any blank lines or lines starting with a
.Ql #
character in this file are ignored.
Each non-comment line of this file must be in one of two formats.
The first format is
.Ql !xx ,
and specifies that device names matching
.Pa /dev/xx*
should not be included in expansion of wildcards (see below).
The second format consists of four white space separated
fields,
which are the full pathname of the disk device,
the size of this disk,
the frequency in days at which to check this disk,
and the rate in kilobytes per second at which to check this disk.
.Pp
Either the frequency or the rate should be specified, not both,
since a specified frequency will be internally converted to whatever
rate will result in the disk being scanned at (approximately) that
frequency.
The size of the disk should not be specified if the rate is specified,
since the size is used only to convert a specified frequency into a rate.
.Pp
If the disk is specified as
.Dq * ,
then
.Nm
will apply the given settings to all disks in the system,
obtained using the
.Va kern.disks
sysctl variable.
If the size is specified as
.Dq *
(recommended),
then the size of the disk will be automatically determined from the
disklabel,
if possible.
Fields which are not specified should contain a single
.Dq *
character.
.Pp
Note that
.Nm
always reads data from the disk in 64KB blocks,
so the rate you specify may not be the exact rate at which the disk is
actually checked.
Similarly,
if you specify the third field (days for complete scan) it is unlikely
that a complete scan will actually take exactly this many days.
.Pp
To run
.Nm
automatically at boot time,
the
.Va diskcheckd_enable
variable in
.Xr rc.conf 5
should be set to
.Dq YES .
.Pp
When
.Nm
receives a
.Dv SIGTERM
or
.Dv SIGINT
signal,
it saves its current state information to a file,
so that after a reboot
.Nm
can resume reading from where it left off,
rather than starting from the beginning of the disk again.
The information saved to this file consists of the device filename and the
current offset into that device.
.Pp
.Nm
can be instructed to reload the configuration file by sending it a
.Dv SIGHUP
signal.
.Pp
.Nm
accepts the following command line options:
.Bl -tag -width Fl
.It Fl d
If this flag is specified,
.Nm
will not fork into the background and detach from its controlling terminal
to become a daemon,
and it will duplicate its system log messages on its standard error output.
.Pp
This flag is primarily used for debugging,
and may be specified more than once.
Additional instances will result in additional
debugging messages on standard error;
these added messages will not be written to the system log.
.It Fl f
Specify the configuration file to use,
instead of the default
.Pa /usr/local/etc/diskcheckd.conf .
.It Fl o
Specify the file to save disk offsets to,
instead of the default
.Pa /var/db/diskcheckd.offsets .
.El
.Sh PROGRESS REPORTING
After every 5 minutes or so of sleep time between reads
(not including time spent waiting for the reads themselves to complete),
.Nm
will update its command parameter space to show its progress
in scanning each disk. This report can be viewed using
.Xr ps 1 .
.Sh FILES
.Bl -tag -width /var/db/diskcheckd.offsets -compact
.It Pa /usr/local/etc/diskcheckd.conf
Default configuration file.
.It Pa /var/db/diskcheckd.offsets
Default location of saved offsets.
.El
.Sh EXAMPLES
To check all of
.Pa /dev/ad0
for errors once every two weeks,
use this entry in
.Pa diskcheckd.conf :
.Bd -literal -offset indent
/dev/ad0 * 14 *
.Ed
.Pp
To check the first SCSI disk for errors at approximately 64KB/s,
use the following entry:
.Bd -literal -offset indent
/dev/da0 * * 64
.Ed
.Pp
To check all disks once every four weeks:
.Bd -literal -offset indent
* * 28 *
.Ed
.Sh DIAGNOSTICS
If any errors occur,
they will be written to
.Xr syslogd 8 .
.Sh HISTORY
.Nm
first appeared in
.Fx 5.0 .
.Sh AUTHORS
.An -nosplit
.Nm
and this manual page were written by
.An Ben Smithurst Aq ben@FreeBSD.org ,
with input from
.An Poul-Henning Kamp Aq phk@FreeBSD.org .
.Sh BUGS
.Nm
assumes all disks have 512 byte sectors.
.Pp
The code that attempts to identify and report which slice and partition
contain a detected error does not understand GPT partitions.