fence_scsi - I/O fencing agent for SCSI persistent reservations
fence_scsi is an I/O fencing agent that uses SCSI-3 persistent
reservations to control access to shared storage devices. These
devices must support SCSI-3 persistent reservations (SPC-3 or greater)
as well as the "preempt-and-abort" subcommand.
The fence_scsi agent works by having each node in the cluster register
a unique key with the SCSI devive(s). Once registered, a single node
will become the reservation holder by creating a "write exclusive,
registrants only" reservation on the device(s). The result is that
only registered nodes may write to the device(s). When a node failure
occurs, the fence_scsi agent will remove the key belonging to the
failed node from the device(s). The failed node will no longer be able
to write to the device(s). A manual reboot is required.
Keys are either be specified manually (see -k option) or generated
automatically (see -n option). Automatic key generation requires that
cman be running. Keys will then be generated using the cluster ID and
node ID such that each node has a unique key that can be determined by
any other node in the cluster.
Devices can either be specified manually (see -d option) or discovered
automatically. Multiple devices can be specified manually by using a
comma-separated list. If no devices are specified, the fence_scsi
agent will attempt to discover devices by looking for cluster volumes
and extracting the underlying devices. Devices may be device-mapper
multipath devices or raw devices. If using a device-mapper multipath
device, the fence_scsi agent will find the underlying devices (paths)
and created registrations for each path.
Fencing action. This value can be "on", "off", or "status". All
actions require either a key (see -k option) or node name (see -n
option). For "on", the agent will attempt to register with the
device(s) and create a reservation if none exists. The "off" action
will attempt to remove a node's key from the device(s). The "status"
action will report whether or not a node's key is currently register
with one or more of the devices. The default action if "off".
List of devices to use for current operation. Devices can be
comma-separated list of raw device (eg. /dev/sdc) or device-mapper
multipath devices (eg. /dev/dm-3). Each device must support SCSI-3
Log output to file.
Name of the node to be fenced. The node name is used to generate the
key value used for the current operation. This option will be ignored
when used with the -k option.
Key to use for the current operation. This key should be unique to a
node. For the "on" action, the key specifies the key use to register
the local node. For the "off" action, this key specifies the key to be
removed from the device(s).
Use the APTPL flag for registrations. This option is only used for the
Print out a help message describing available options, then exit.
Print out a version message, then exit.
agent = "param"
This option is used by fence_node(8) and is ignored by fence_scsi.