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Sun Cluster System Administration Guide for Solaris OS

Administering the SCSI Protocol Settings for Storage Devices

Sun Cluster software installation automatically assigns SCSI reservations to all storage devices. Use the following procedures to check the settings of devices and, if necessary, to override the setting for a device.

ProcedureHow to Display the Default Global SCSI Protocol Settings for All Storage Devices

The phys-schost# prompt reflects a global-cluster prompt. Perform this procedure on a global cluster.

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the long and short forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix B, Sun Cluster Object-Oriented Commands.

  1. Become superuser or assume a role that provides solaris.cluster.read RBAC authorization.

  2. From any node, display the current global default SCSI protocol setting.


    # cluster show -t global

    For more information, see the cluster(1CL) man page.

Example 5–38 Displaying the Default Global SCSI Protocol Settings for All Storage Devices

The following example displays the SCSI protocol settings for all storage devices on the cluster.


# cluster show -t global

=== Cluster ===                                

Cluster Name:                                   racerxx
  installmode:                                    disabled
  heartbeat_timeout:                              10000
  heartbeat_quantum:                              1000
  private_netaddr:                                172.16.0.0
  private_netmask:                                255.255.248.0
  max_nodes:                                      64
  max_privatenets:                                10
  global_fencing:                                 pathcount
  Node List:                                      phys-racerxx-1, phys-racerxx-2

ProcedureHow to Display the SCSI Protocol of a Single Storage Device

The phys-schost# prompt reflects a global-cluster prompt. Perform this procedure on a global cluster.

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the long and short forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix B, Sun Cluster Object-Oriented Commands.

  1. Become superuser or assume a role that provides solaris.cluster.read RBAC authorization.

  2. From any node, display the SCSI protocol setting of the storage device.


    # cldevice show device
    device

    The name of the device path or a device name.

    For more information, see the cldevice(1CL)man page.

Example 5–39 Displaying the SCSI Protocol of a Single Device

The following example displays the SCSI protocol for the device /dev/rdsk/c4t8d0.


# cldevice show /dev/rdsk/c4t8d0


=== DID Device Instances ===                   

DID Device Name:                                /dev/did/rdsk/d3
  Full Device Path:                               phappy1:/dev/rdsk/c4t8d0
  Full Device Path:                               phappy2:/dev/rdsk/c4t8d0
  Replication:                                    none
  default_fencing:                                global

ProcedureHow to Change the Default Global Fencing Protocol Settings for All Storage Devices

You can turn fencing on or off globally for all storage devices connected to a cluster. The default fencing setting of a single storage device overrides the global setting when the device's default fencing is set to pathcount, prefer3. or nofencing. If the default fencing setting of a storage device is set to global, the storage device will use the global setting. For example, if a storage device has the default setting pathcount, the setting will not change if you use this procedure to change the global SCSI protocol settings to prefer3. You must use the How to Change the Fencing Protocol for a Single Storage Device procedure to change the default setting of a single device.

Caution – Caution –

If fencing is turned off under the wrong circumstances, your data can be vulnerable to corruption during application failover. Examine this data corruption possibility carefully when you are considering turning fencing off. Fencing can be turned off if the shared storage device does not support the SCSI protocol or if you want to allow access to the cluster's storage from hosts outside the cluster.

To change the default fencing setting for a quorum device, you must unconfigure the device, change the fencing setting, and reconfigure the quorum device. If you plan to turn fencing off and back on regularly for devices that include quorum devices, consider configuring quorum through a quorum server service to eliminate interruptions in quorum operation.

The phys-schost# prompt reflects a global-cluster prompt. Perform this procedure on a global cluster.

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the long and short forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix B, Sun Cluster Object-Oriented Commands.

  1. Become superuser or assume a role that provides solaris.cluster.modify RBAC authorization.

  2. Set the fencing protocol for all storage devices that are not quorum devices.


    cluster set -p global_fencing={pathcount | prefer3 | nofencing | nofencing-noscrub}
    -p global_fencing

    Sets the current global default fencing algorithm for all shared devices.

    prefer3

    Uses the SCSI-3 protocol for devices with more than two paths.

    pathcount

    Determines the fencing protocol by the number of DID paths that are attached to the shared device. The pathcount setting is used for quorum devices.

    nofencing

    Turns fencing off by setting the fencing status for all storage devices.

    nofencing-noscrub

    Scrubbing the device ensures that the device is cleared of all persistent SCSI reservation information and allows access to the storage from systems outside the cluster. Use the nofencing-noscrub option only for storage devices that have severe problems with SCSI reservations.

Example 5–40 Setting the Default Global Fencing Protocol Settings for All Storage Devices

The following example sets the fencing protocol for all storage devices on the cluster to the SCSI-3 protocol.


# cluster set -p global_fencing=prefer3

ProcedureHow to Change the Fencing Protocol for a Single Storage Device

You can also set the fencing protocol for a single storage device.

Note –

To change the default fencing setting for a quorum device, you must unconfigure the device, change the fencing setting, and reconfigure the quorum device. If you plan to turn fencing off and back on regularly for devices that include quorum devices, consider configuring quorum through a quorum server service to eliminate interruptions in quorum operation.

The phys-schost# prompt reflects a global-cluster prompt. Perform this procedure on a global cluster.

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the long and short forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix B, Sun Cluster Object-Oriented Commands.

Caution – Caution –

If fencing is turned off under the wrong circumstances, your data can be vulnerable to corruption during application failover. Examine this data corruption possibility carefully when you are considering turning fencing off. Fencing can be turned off if the shared storage device does not support the SCSI protocol or if you want to allow access to the cluster's storage from hosts outside the cluster.

  1. Become superuser or assume a role that provides solaris.cluster.modify RBAC authorization.

  2. Set the fencing protocol of the storage device.


    cldevice set -p default_fencing ={pathcount | scsi3 | global | nofencing | nofencing-noscrub} device
    -p default_fencing

    Modifies the default_fencing property of the device.

    pathcount

    Determines the fencing protocol by the number of DID paths that are attached to the shared device.

    scsi3

    Uses the SCSI-3 protocol.

    global

    Uses the global default fencing setting. The global setting is used for non-quorum devices.

    Turns fencing off by setting the fencing status for the specified DID instance.

    nofencing-noscrub

    Scrubbing the device ensures that the device is cleared of all persistent SCSI reservation information and allows access to the storage device from systems outside the cluster. Use the nofencing-noscrub option only for storage devices that have severe problems with SCSI reservations.

    device

    Specifies the name of the device path or device name.

    For more information, see the cluster(1CL) man page.

Example 5–41 Setting the Fencing Protocol of a Single Device

The following example sets the device d5, specified by device number, to the SCSI-3 protocol.


# cldevice set -p default_fencing=prefer3 d5

The following example turns default fencing off for the d11 device.


#cldevice set -p default_fencing=nofencing d11