cf – controls the takeover and giveback operations of the filers in a cluster
cf [ disable | enable | forcegiveback | forcetakeover [ -df ] | giveback [ -f ] | hw_assist [ status | test stats [ clear ] ] | monitor | partner | status [ -t ] takeover [ -f ] | [ -n ]]
cf nfo [ enable | disable ] disk_shelf
cf nfo status
The cf command controls the cluster failover monitor, which determine when takeover and giveback operations take place within a cluster.
The cf command is available only if your filer has the cluster license.
- Disables the takeover capability of both filers in the cluster.
- Enables the takeover capability of both filers in the cluster.
- forcegiveback is dangerous and can lead to data corruption; in almost all cases, use cf giveback -f instead.
Forces the live filer to give back the resources of the failed filer even though the live filer determines that doing so might result in data corruption or cause other severe problems. giveback will refuse to giveback under these conditions. Using the forcegiveback option forces a giveback. When the failed filer reboots as a result of a forced giveback, it displays the following message:
partner giveback incomplete, some data may be lost
forcetakeover [-f] forcetakeover is dangerous and can lead to data corruption; in almost all cases, use cf takeover instead.
Forces one filer to take over its partner even though the filer detects an error that would otherwise prevent a takeover. For example, normally, if a detached or faulty ServerNet cable between the filers causes the filers’ NVRAM contents to be unsynchronized, takeover is disabled. However, if you enter the cf forcetakeover command, the filer takes over its partner despite the unsynchronized NVRAM contents. This command might cause the filer being taken over to lose client data. If you use the -f option, the cf command allows such a forcetakeover to proceed without requiring confirmation by the operator.
forcetakeover -d[f] Forces a filer to take over its partner in all cases where a forcetakeover would fail. In addition it will force a takeover even if some partner mailbox disks are inaccessible. It can only be used when cluster_remote is licensed.
forcetakeover -d is very dangerous. Not only can it cause data corruption, if not used carefully, it can also lead to a situation where both the filer and it’s partner are operational (split brain). As such, it should only be used as a means of last resort when the takeover and forcetakeover commands are unsuccessful in achieving a takeover. The operator must ensure that the partner filer does not become operational at any time while a filer is in a takeover mode initiated by the use of this command. In conjunction with RAID mirroring, it can allow recovery from a disaster when the two filers in the cluster are located at two distant sites. The use of -f option allows this command to proceed without requiring confirmation by the operator.
- giveback [ -f ]
- Initiates a giveback of partner resources. Once the giveback is complete, the automatic takeover capability is disabled until the partner is rebooted. A giveback fails if outstanding CIFS sessions, active system dump processes, or other filer operations makes a giveback dangerous or disruptive. If you use the -f option, the cf command allows such a giveback to proceed as long as it would not result in data corruption or filer error.
hw_assist [ status | test | stats [ clear ] ] Displays information related to the hardware-assisted takeover functionality. Use the cf hw_assist status command to display the hardware-assisted functionality status of the local as well as the partner filer. If hardware-assisted status is inactive, the command displays the reason and if possible, a corrective action. Use the cf hw_assist test command to validate the hardware-assisted takeover configuration. An error message is printed if hardware-assisted takeover configuration can not be validated. Use the cf hw_assist stats command to display the statistics for all hw_assist alerts received by the filer. Use cf hw_assist stats clear to clear hardware-assisted functionality statistics.
- Displays the time, the state of the local filer and the time spent in this state, the host name of the partner and the state of cluster failover monitor (whether enabled or disabled). If the partner has not been taken over currently, the status of the partner and that of the interconnect are displayed and any ongoing giveback or scheduled takeover operations are reported.
- Displays the host name of the partner. If the name is unknown, the cf command displays “partner.”
- Displays the current status of the local filer and the cluster. If you use the -t option, displays the status of the node as time master or slave.
takeover [ -f ] | [ -n ]
Initiates a takeover of the partner. If you use the -f option, the cf command allows such a takeover to proceed even if it will abort a coredump on the other filer.
If you use the -n option, the cf command allows a takeover to proceed even if the partner node was running an incompatible version of Data ONTAP. The partner node must be cleanly halted in order for this option to succeed. This is used as part of a nondisruptive upgrade process.
nfo [ enable | disable ] disk_shelf
Enables or disables negotiated failover on disk shelf count mismatch.
This command is obsolete. Option cf.takeover.on_disk_shelf_miscompare replaces it.
Negotiated failover is a general facility which supports negotiated failover on the basis of decisions made by various modules. disk_shelf is the only negotiated failover module currently implemented. When communication is first established over the interconnect between the local filer and its partner, a list of disk shelves seen by each node on its A and B loops is exchanged. If a filer sees that the count of shelves that the partner sees on its B loops is greater than the filer’s count of shelves on its A loops, the filer concludes that it is “impaired” (as it sees fewer of its shelves than its partner does) and asks the partner to take it over. If the partner is not itself impaired, it will accept the takeover request and, in turn, ask the requesting filer to shut down gracefully. The partner takes over after the requesting node shuts down, or after a time-out period of approximately 3 minutes expires. The comparison of disk shelves is only done when communication between the filers is established or re-established (for example, after a node reboots).
- nfo status
- Displays the current negotiated failover status.
This command is obsolete. Use cf status instead.