6.12.1 Configuring a shared disk

(a) Creating volume groups

(b) Editing the /etc/rc.sysinit file

This subsection explains editing of the /etc/rc.sysinit file.

• When using LVM for switchover processing

  Search the file for the lines that contain "/sbin/lvm vgchange -a y" or "/sbin/lvm vgchange -a ay", and then delete "/sbin/lvm.static vgchange -a y --ignorelockingfailure".

  If a command to be executed by action is deleted as a result of the above deletion, either delete action itself or comment it out. If deletion of action results in deletion of a command that is executed by the then clause of the if command, insert a null line by using a colon (:) to avoid shell syntax errors.

  If the volume group contains a resource other than the shared disk to which you want to connect automatically for referencing and updating at system startup, add the following information immediately after the deleted line: "/sbin/lvm.static vgchange -a y name-of-volume-group-to-be-connected --sysinit" or "/sbin/lvm vgchange -a ay name-of-volume-group-to-be-connected --sysinit".

Important

Use special caution when editing the /etc/rc.sysinit file. If you edit it incorrectly, the system might be unable to start. For example, the system becomes unable to start in the following cases:

• The /etc/rc.sysinit file is incorrectly edited and a shell syntax error occurs.

• LVM is allocated in /root, /home, or another area that is required for startup and connection by the vgchange -a y command is not specified in the /etc/rc.sysinit file.

After editing the /etc/rc.sysinit file, if you update the initscripts package of Red Hat Enterprise Linux, the /etc/rc.sysinit file might be overwritten. If the file is overwritten, the changes to the file are lost. If the changes to the /etc/rc.sysinit file are lost, you must edit it again.

The following subsection presents examples of editing the /etc/rc.sysinit file.

(c) Examples of editing the /etc/rc.sysinit file (when using LVM)

This subsection presents examples of editing the /etc/rc.sysinit file when using LVM.

The following show an example when the OS being used is Red Hat Enterprise Linux 6.1.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
    action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a y --sysinit
fi
.
.

After editing (when the volume group is not to be connected automatically for referencing and updating)

.
.
  if [ -x /sbin/lvm ]; then
#     action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a y --sysinit
    :
  fi
.
.

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
#    action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a y --sysinit
     /sbin/lvm vgchange -a y vg01 --sysinit
     /sbin/lvm vgchange -a y vg02 --sysinit
    :
fi
.
.

The following shows an example when the OS being used is Red Hat Enterprise Linux 6.4.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
    action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit
fi
.
.

After editing (when not connecting the volume groups automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
#     action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit
     :
fi
.
.

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
#    action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit
     /sbin/lvm vgchange -a ay vg01 --sysinit
     /sbin/lvm vgchange -a ay vg02 --sysinit
fi
.
.

The following shows an example of when the OS being used is Red Hat Enterprise Linux 6.6, 6.7, 6.8, 6.9, or 6.10.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
    if [ ! -f /.nolvm ] && ! strstr "$cmdline" nolvm ; then
        action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit --ignoreskippedcluster
    else
        echo $"Logical Volume Management disabled at boot."
    fi
fi
.
.

After editing (when the volume group is not to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
    if [ ! -f /.nolvm ] && ! strstr "$cmdline" nolvm ; then
#        action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit --ignoreskippedcluster
   :
    else
        echo $"Logical Volume Management disabled at boot."
    fi
fi
.
.

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

.
.
if [ -x /sbin/lvm ]; then
    if [ ! -f /.nolvm ] && ! strstr "$cmdline" nolvm ; then
#        action $"Setting up Logical Volume Management:" /sbin/lvm vgchange -a ay --sysinit --ignoreskippedcluster
         /sbin/lvm vgchange -a ay vg01 --sysinit --ignoreskippedcluster
         /sbin/lvm vgchange -a ay vg02 --sysinit --ignoreskippedcluster
    else
        echo $"Logical Volume Management disabled at boot."
    fi
fi
.
.

(d) Editing the /etc/lvm/lvm.conf file

Edit the "auto_activation_volume_list" entry in the /etc/lvm/lvm.conf file so that the shared disks controlled by HA Monitor are controlled as follows:

• Volume groups controlled by HA Booster (volume groups on a device registered in a control group):

  The volume groups are automatically connected for referencing and updating (that is, activated) when the system starts.

• Volume groups not controlled by HA Booster:

  The volume groups are not automatically connected for referencing and updating (that is, activated) when the system starts.

(e) Examples of editing the /etc/lvm/lvm.conf file

This subsection presents examples of editing the /etc/lvm/lvm.conf file when using LVM.

The following shows an example when the OS being used is Red Hat Enterprise Linux Server 7.1.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

activation {
...
...
# If auto_activation_volume_list is defined but empty, no volumes will be
# activated automatically and --activate ay/-a ay will do nothing.
#
# auto_activation_volume_list = []
 
# If auto_activation_volume_list is defined and it's not empty, only matching
# volumes will be activated either automatically or by using --activate ay/-a ay.
#
# "vgname" and "vgname/lvname" are matched exactly.
# "@tag" matches any tag set in the LV or VG.
# "@*" matches if any tag defined on the host is also set in the LV or VG
#
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
...
...
}

After editing (when no volume groups are to be connected automatically for referencing and updating)

activation {
...
...
# If auto_activation_volume_list is defined but empty, no volumes will be
# activated automatically and --activate ay/-a ay will do nothing.
#
# auto_activation_volume_list = []
 
# If auto_activation_volume_list is defined and it's not empty, only matching
# volumes will be activated either automatically or by using --activate ay/-a ay.
#
# "vgname" and "vgname/lvname" are matched exactly.
# "@tag" matches any tag set in the LV or VG.
# "@*" matches if any tag defined on the host is also set in the LV or VG
#
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
 
auto_activation_volume_list = []
...
...
}

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

activation {
...
...
# If auto_activation_volume_list is defined but empty, no volumes will be
# activated automatically and --activate ay/-a ay will do nothing.
#
# auto_activation_volume_list = []
 
# If auto_activation_volume_list is defined and it's not empty, only matching
# volumes will be activated either automatically or by using --activate ay/-a ay.
#
# "vgname" and "vgname/lvname" are matched exactly.
# "@tag" matches any tag set in the LV or VG.
# "@*" matches if any tag defined on the host is also set in the LV or VG
#
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
 
auto_activation_volume_list = [ "vg01", "vg02" ]
...
...
}

The following shows an example when the OS being used is Red Hat Enterprise Linux Server 7.2.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
        # Configuration option activation/auto_activation_volume_list.
        # Only LVs selected by this list are auto-activated.
...
...
        # Example
        # volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
        # 
        # This configuration option does not have a default value defined.
...
...
}

After editing (when no volume groups are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
        # Configuration option activation/auto_activation_volume_list.
        # Only LVs selected by this list are auto-activated.
...
...
        # Example
        # volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
        # 
        # This configuration option does not have a default value defined.

    auto_activation_volume_list = []
...
...
}

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
        # Configuration option activation/auto_activation_volume_list.
        # Only LVs selected by this list are auto-activated.
...
...
        # Example
        # volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
        # 
        # This configuration option does not have a default value defined.

    auto_activation_volume_list = [ "vg01", "vg02" ]
...
...
}

The following shows an example when the OS is Red Hat Enterprise Linux Server version 7.3 to 7.7 or 8.1 to 8.5.

Before editing (when all volume groups in the system are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
# Configuration option activation/auto_activation_volume_list.
...
...
# Example
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
#
# This configuration option does not have a default value defined.
...
...
}

After editing (when no volume groups are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
# Configuration option activation/auto_activation_volume_list.
...
...
# Example
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
#
# This configuration option does not have a default value defined.
auto_activation_volume_list = []
...
...
}

After editing (when vg01 and vg02 are to be connected automatically for referencing and updating)

# Configuration section activation.
activation {
...
...
# Configuration option activation/auto_activation_volume_list.
...
...
# Example
# auto_activation_volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]
#
# This configuration option does not have a default value defined.
auto_activation_volume_list = [ "vg01", "vg02" ]
...
...
}

(a) Timing of issuance of a user command

Specify a user command in such a manner that the raw OS command is issued at the following times:

(b) Coding example for a user command

This coding example for a user command binds a character special file (/dev/raw/raw1) to a logical volume (lvol0) on a shared disk (/dev/vg10) for a server (LinuxTP1).

This code is stored under the file name usrcommand_raw_bind in HA Monitor's sample file directory.

#! /bin/sh
 
# The definition of server
SERV="LinuxTP1"                  # server name:LinuxTP1
# user name
USER_NAME="TP1user"              # user name, TPI administrator, or HiRDB administrator
# The definition of device
RAW_NAME="/dev/raw/raw1"         # raw device name
DEV_NAME="/dev/vg10/lvol0"       # the name of logical volume on shared disk
 
# Unbinding the raw device
func_unbind(){
# Wait to unbind the raw device.
COUNT=0
while [ \( ${COUNT} -lt 10 \) -a \( -e "$1" \) ]
do
   # Kill processes accessing the raw device.
   fuser -k "$1" >/dev/null 2>&1
   # Wait for 1 second until processing finishes.
   sleep 1
   # Unbind the raw device.
   raw "$1" 0 0
   COUNT=`expr ${COUNT} + 1`
done
}
 
# Binding the raw device
func_bind(){
# Bind the raw device.
raw "$1" "$2"
# Wait to bind the raw device.
COUNT=0
while [ ${COUNT} -lt 10 ]
do
   # If the raw device can be read, finish binding.
   dd of=/dev/null if="$1" bs=1 count=0 >/dev/null 2>&1
   if [ "$?" = 0 ]
   then
     break
   fi
   # Wait for 1 second until the raw device sets.
   sleep 1
   COUNT=`expr ${COUNT} + 1`
done
# Change the owner of the device
chown $USER_NAME "$1"
}
# Main
# Bind the raw device, when the online server starts or Hotstandby is started.
# Unbind the raw device, when the online server ends, standby server starts
# or Hotstandby is failed.
PATH=/bin:/usr/bin:/sbin
export PATH
if [ "$2" = "${SERV}" ]
then
   if [ "$4" = "online" ]
   then
     case "$5" in
     "-s" )                      # online server startup
       if [ "$6" = "start" ]
       then
         func_bind ${RAW_NAME} ${DEV_NAME}
       fi
     ;;
     "-a" | "-w" | "-o" | "-e" | "-p" )  # online server end
                                 # (server error | planned system switch
                                 # | server error (no standby server)
                                 # | normal end | planned stop)
       if [ "$6" = "start" ]
       then
         func_unbind ${RAW_NAME} ${DEV_NAME}
       fi
     ;;
     esac
   else
     case "$5" in
     "-a" | "-h" | "-w" )        # Standby server is done into Hotstandby.
                                 # (server error | host down | planned system switch)
       if [ "$6" = "start" ]
       then
         func_bind ${RAW_NAME} ${DEV_NAME}
       fi
     ;;
     "-s" | "-f" )               # standby server startup or Hotstandby fail
       if [ "$6" = "start" ]
       then
         func_unbind ${RAW_NAME} ${DEV_NAME}
       fi
     ;;
     esac
   fi
fi

This coding example binds a character special file by executing func_bind in the active system when the active server starts or on the target host when hot standby processing is performed. It also unbinds the character special file by executing func_unbind in the active system when the active server terminates, in a standby system when the standby server starts, or in a standby system resulting in a hot standby error in the event that hot standby processing fails.

func_bind uses the raw command to bind a character special file. After that, func_bind retries the following processing once a second (for a maximum of 10 seconds) until the character special file becomes accessible:

• dd command

  Checks whether the character special file has become accessible.

• sleep command

  Waits until the character special file is bound.

• chown command

  Changes the owner of the character special file. Note that if the OS is RHEL6 or later, you do not need to use a user command to change the owner. You can change the owner by using the udev function of the OS. For details about the udev settings, see the documentation for the OS.

In addition, the owner of the bound character special file is set to the specified user.

func_unbind retries the following processing once a second (for a maximum of 10 seconds) until the character special file is unbound:

• fuser command

  If a process is using the character special file during hot standby processing, disconnection of the shared disk fails because the character special file cannot be unbound. Therefore, the fuser command is used to forcibly terminate all processes that are using the character special file.

• sleep command

  Waits until the character special file is unbound.

• raw command

  Unbinds the character special file.

Note that in this coding example, if bind processing takes 10 seconds or longer for any reason, the chown command, which is executed last, fails to change the privilege. If the settings are specified so that server startup processing continues^#, the user cannot notice the error until the server accesses a raw device.

#

uoc_neck is omitted or nouse is specified in the server environment settings.

To prevent this, consider the following measures:

• In the server environment settings, specify use for uoc_neck so that server startup processing stops when the chown command fails to change the privilege.

  In the sample user command, the result of the chown command, which is executed last, is the result of the user command. However, if you change the sample processing (for example, processing is added after the chown command), make sure that the results of the chown command and other processing are reflected to the final result of the user command.

• If you do not set use for uoc_neck in the server environment settings, add processing that outputs a message to syslog or another location to the user command as a means for error notification.

• If necessary, change the interval at which processing is retried until the character special file becomes accessible.