I/O fencing Implementation on Existing clusters

I/O fencing Implementation on Existing clusters

I/O Fencing Service/Driver:

I/O fencing uses GAB port b for communication. Fencing is started with the vxfenconfig -c command. The fencing driver vxfen is started during system start up using /etc/rc2.d/s97vxfen. 

Configuration Files for I/O fencing:

1.  /etc/vxfenbtab

2.  /etc/vxfendg

3.  /etc/vxfenmode

I/O fencing Implementation on Existing clusters

1.    Configure coordinator diskgroup using SCSI-3 Persistent Reservations LUNS .(Most of the SAN supports SCSI-3 PR)

2.    Set coordinator flag to the diskgroup

#vxdg -g fendg set coordinator=on

3.    Fencing Supports DMP for coordinator and data disks. Set policy in /etc/vxfenmode.
Perform the below on each cluster nodes.

# mv  /etc/vxfenmode  /etc/vxfenmode.previous # cp  /etc/vxfen.d/vxfenmode_scis3_dmp /etc/vxfenmode # cat /etc/vxfenmode vxfen_mode=scsi3 scsi3_disk_policy=dmp

4.    Deport the diskgroup. “-t” turns off automatic importing when system starts.

# vxdg deport fendg # vxdg -t import fendg # vxdg deport fendg

5.    Create /etc/vxfendg on all cluster nodes

# echo "fendg" > /etc/vxfendg

6.    Test the diskgroup for I/O fencing compatibility.
Option “-r” will run the test in non-destructive mode.

boxnet2#/opt/VRTSvcs/vxfen/bin/vxfentsthdw -r -g fendg VERITAS vxfentsthdw version 5.1 Solaris The utility vxfentsthdw works on the two nodes of the cluster. The utility verifies that the shared storage one intends to use is configured to support I/O fencing.  It issues a series of vxfenadm commands to setup SCSI-3 registrations on the disk, verifies the registrations on the disk, and removes the registrations from the disk. The logfile generated for vxfentsthdw is /var/VRTSvcs/log/vxfen/vxfentsthdw.log.11074 Enter the first node of the cluster: node1 Enter the second node of the cluster: node2 ******************************************** Testing node1 /dev/vx/rdmp/disk_4s2 node2 /dev/vx/rdmp/disk_7s2 Evaluate the disk before testing  ........................ No Pre-existing keys RegisterIgnoreKeys on disk /dev/vx/rdmp/disk_4s2 from node node1 ....... Passed Verify registrations for disk /dev/vx/rdmp/disk_4s2 on node node1 ...... Passed RegisterIgnoreKeys on disk /dev/vx/rdmp/disk_7s2 from node node2 ....... Passed Verify registrations for disk /dev/vx/rdmp/disk_7s2 on node node2 ...... Passed Unregister keys on disk /dev/vx/rdmp/disk_4s2 from node node1 .......... Passed Verify registrations for disk /dev/vx/rdmp/disk_7s2 on node node2 ...... Failed Unregistration test for disk  failed on node node2.          Unregistration from one node is causing unregistration of keys from the other node.         Disk  is not SCSI-3 compliant on node node2.         Execute the utility vxfentsthdw again and if failure persists contact         the vendor for support in enabling SCSI-3 persistent reservations Removing test keys and temporary files, if any...

The above test should be password in a order to use the diskgroup as coordinator DG.
Note: As the above results, my test is failed due to SCSI-3 PR issue.

7.    Start the fencing driver using script on all cluster nodes.

# /sbin/vxfen-startup

Node:/etc/vxfentab  will be updated whenever fencing driver re-initializes. 

Close the cluster configuration on all the cluster nodes.

# haconf -dump -makero

8.    Perform the offline configuration (i.e. modify main.cf using vi editor) to add “UseFence = SCSI3″ line under the bottom of cluster Name

cluster BOXNET UserNames = { admin = “ABCDGFRFSLK.” } Administrators = { admin } ClusterAddress = “192.168.2.7″ UseFence = SCSI3 )

9.    Stop VCS on all cluster nodes.

# hastop -all

10. Restart VCS on all the cluster nodes.

# hastart

11.  Display the fencing membership status

# vxfenadm -d I/O Fencing Cluster Information: ================================ Fencing Protocol Version: 201 Fencing Mode: SCSI3 Fencing SCSI3 Disk Policy: dmp Cluster Members: * 0 (boxnet1)   1 (boxnet2) RFSM State Information: node 0 in state 8 (running) node 1 in state 8 (running)

For your information, we can configure I/O fencing using CLI option as well, 

./installvcs -fencing

Thank you for reading.

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