md_monitor man page on SuSE

Man page or keyword search:  
man Server   14857 pages
apropos Keyword Search (all sections)
Output format
SuSE logo
[printable version]

md_monitor(8)							 md_monitor(8)

NAME
       md_monitor - MD device monitor

SYNOPSIS
       md_monitor  [-d|--daemonize]  [-f  file|--file  file] [-s|--syslog] [-e
       num|--expires=num]  [-l	 num|--process-limit=num]   [-m|--fail-mirror]
       [-o|--fail-disk]	 [-r  num|--retries=num] [-p prio|--log-priority=prio]
       [-v|--verbose] [-y|--check-in-sync] [-c	cmd|--command=cmd]  [-V|--ver‐
       sion] [-h|--help]

DESCRIPTION
       The  md_monitor monitors the component devices of each MD array for I/O
       issues. It will update the monitored MD arrays on each  status  change,
       setting devices to 'faulty' or re-integrate working devices.

OPTIONS
       md_monitor recognizes the following command-line options:

       -d, --daemonize
	      Start md_monitor in background

       -f file, --logfile=file
	      Write logging information into file instead of stdout

       -s, --syslog
	      Write logging information to syslog.

       -e num, --expires=num
	      Set failfast_expires to num.

       -l num, --process-limit=num
	      Set maximum number of processes (RLIMIT_NPROC, see getrlimit(2))
	      to num.

       -m, --fail-mirror
	      Fail and reset the entire mirror half when  one  device  failed.
	      This is the default.

       -o, --fail-disk
	      Only fail the affected disk when one device failed.  This is the
	      opposite of --fail-mirror.

       -r num, --retries=num
	      Set failfast_retries to num.

       -p prio, --log-priority=prio
	      Set logging priority to prio.

       -t secs, --check-timeout=secs
	      Run path checker every secs seconds. Default is 1.

       -v, --verbose
	      Increase logging priority

       -y, --check-in-sync
	      Run path checkers for 'in_sync'  devices.	 Without  this	option
	      path  checkers  will be stopped whenever a device is detected to
	      be 'in_sync'. They will be re-started once  a  device  has  been
	      marked as 'faulty' or 'timeout'.

       -c cmd, --command=cmd
	      Send command cmd to daemon.

       -h, --help
	      Display md_monitor usage information.

       -V, --version
	      Display md_monitor version information.

MD_MONITOR COMMAND MODE
       When  specifying --command the md_monitor program connects to a already
       running md_monitor program and send a pre-defined command. The  command
       has the following syntax:

       cmd:md@dev

       The  following  values  for cmd are recognised. If not specified other‐
       wise, md needs to be the device node of an existing MD array.

       Shutdown
	      Shutdown md_monitor; md argument should be /dev/console

       RebuildStarted
	      Rebuild has started on array md.

       RebuildFinished
	      Rebuild has finished on array md.

       DeviceDisappeared
	      MD array has been stopped; md_monitor will stop  monitoring  the
	      component devices for that array.

       Fail   MD  detected  a failure on the component device dev of array md.
	      md_monitor will re-check the device every failfast_expires  sec‐
	      onds.

       Remove The  component device dev has been removed from the MD array md.
	      md_monitor will stop monitoring this device.

       SpareActive
	      MD has integrated the device dev into array md. md_monitor  will
	      re-start	monitoring  of this device every failfast_expires sec‐
	      onds. The check interval will be increased for  each  successful
	      check  up	 to  a	maximum of failfast_expires * failfast_retries
	      seconds.

       ArrayStatus
	      Return the current internal status of the monitored devices.

       MirrorStatus
	      Return the status of the MD  component  devices  in  abbreviated
	      form.   Each character represents the status of the MD component
	      device at that position. For the possible states	see  the  next
	      paragraph.

       MonitorStatus
	      Return  the  current internal status of the monitored devices in
	      abbreviated form. Each character represents the internal	status
	      of the monitored device in abbreviated form.

DEVICE STATUS DISPLAY
       md_monitor  will	 be  displaying	 state information about the monitored
       devices when the CLI command MirrorStatus  or  MonitorStatus  is	 sent.
       Each  character	of  the	 returned  string  represents the state of the
       device at that location.

       The possible states for MirrorStatus are:

       .      Unknown

       A      In_Sync

       W      Faulty

       U      Ready

       S      Spare

       -      Removed

       R      Recovery pending

       P      Removal pending

       R and P are intermediate states, which are set by md_monitor whenever a
       command	has  been sent to mdadm, but no notification has been received
       yet.  U is set when the device is found working, but  --fail-mirror  is
       set and not all devices within the mirror side are found to be working.

       The possible states for MonitorStatus are:

       .      Unknown

       X      Internal error

       A      I/O ok

       W      I/O failed

       R      I/O pending

       T      I/O timeout

       R and T describe the same condition, ie I/O has been stalled. The state
       will switch from R to T when the timeout as set by  failfast_expires  *
       failfast_retries seconds has expired.

THEORY OF OPERATION
       md_monitor  sets up a path checker thread for each MD component device.
       This path checker will issue every check-time seconds  an  asynchronous
       I/O  request  to	 the device. It will then wait up to expires * retries
       seconds for this I/O to complete.  If no	 response  has	been  received
       during that time, the monitor status for this path is set to 'I/O time‐
       out'. If the I/O completed the monitor status for this path will be set
       to  'I/O	 ok'  or  'I/O failed', depending on whether the I/O completed
       without error or not.  If the path checker has been interrupted	during
       waiting, the monitor status for this path will be set to 'I/O pending'.
       After the monitor status has been updated, the path checker thread will
       update the MD status for this device and invoke an action, depending on
       these two states.  If check-in-sync has been specified the path checker
       continue to run even for 'in_sync' paths. Otherwise the path checker be
       stopped when a path is marked as	 'in_sync'.   Path  checkers  will  be
       restarted whenever a device is marked as 'faulty' or 'timeout'.

MDADM INTEGRATION
       md_monitor  listens  to	udev  events  for  any	device	changes. It is
       designed to integrate into MD via the --monitor functionality of mdadm.

       To use this function mdadm needs to be started with

       mdadm --monitor --scan --program=md_script

       where md_script is a bash script containing eg:

       #!/bin/bash
       # MD monitor script
       #

       EVENT=$1
       MD=$2
       DEV=$3

       /sbin/md_monitor -c "${EVENT}:${MD}@${DEV}"

       A default md_script is installed at
       /usr/share/misc/md_notify_device.sh.

       It is recommended to use an /etc/mdadm.conf configuration file
       when using md_monitor to monitor MD arrays.

FILES
       /usr/share/misc/md_notify_device.sh    Default	 md_monitor    script.
       /etc/mdadm.conf MD configuration file

SEE ALSO
       mdadm(8) mdadm.conf(7)

				Wed Mar 14 2012			 md_monitor(8)
[top]

List of man pages available for SuSE

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net