fence_scsi(8) fence_scsi(8)

NAME fence_scsi - I/O fencing agent for SCSI persistent reservations

SYNOPSIS fence_scsi [OPTION]...

DESCRIPTION fence_scsi is an I/O fencing agent that uses SCSI-3 persistent reserva- tions 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, reg- istrants 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. In the cluster environment unfence action should be configured also.

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 multi- path devices or raw devices. If using a device-mapper multipath device, the fence_scsi agent will find the underlying devices (paths) and cre- ated registrations for each path.

OPTIONS -o action Fencing action. This value can be "on", "off", "status", or "metadata". The "on", "off", and "status" 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 nodes key from the device(s). The "status" action will report whether or not a nodes key is currently register with one or more of the devices. The "metadata" action will display the XML metadata. The default action if "off".

-d devices List of devices to use for current operation. Devices can be comma-separated list of raw device (eg. /dev/sdc) or device-map- per multipath devices (eg. /dev/dm-3). Each device must support SCSI-3 persistent reservations.

-f logfile Log output to file.

-n nodename 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.

-k key 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 speci- fies the key to be removed from the device(s).

-H delay Wait X seconds before fencing is started (Default Value: 0)

-a Use the APTPL flag for registrations. This option is only used for the "on" action.

-h Print out a help message describing available options, then exit.

-v Verbose output.

-V Print out a version message, then exit.

STDIN PARAMETERS agent = "param" This option is used by fence_node(8) and is ignored by fence_scsi.

nodename = "param" Same as -n option.

action = "param" Same as -o option.

devices = "param" Same as -d option.

logfile = "param" Same as -f option

key = "param" Same as -k option.

delay = "param" Same as -H option.

aptpl = "1" Enable the APTPL flag. Default is 0 (disable).

SEE ALSO fence(8), fence_node(8), sg_persist(8), vgs(8), cman_tool(8), cman(5)

fence_scsi(8)