I/O Fencing

I/O fencing properties:-


1. At least 3 or odd no of Coordinator disks.
2. SCSI3 persistent reservation support .
3. Separate deported dg with coordinator disks.
Commands :-

/etc/vxfenmode is used to set the mode for coordinator disks.

Disable it :-

root ~~ #>cat /etc/vxfenmode
vxfen_mode=disabled

Enable DMP :-

root ~~ #>cat /etc/vxfenmode
vxfen_mode=scsi3
scsi_disk_policy=dmp

verify if the hard disk supports scsi3 persistent reservation :-

#vxfentsthdw –r –g vxfencoorddg
Initialize coordinator disk group :-
vxdg init -o coordinator=on vxfencoorddg disk1=c1t5d0 disk2=c1t5d1 disk3=c1t5d2
deport dg :-

#vxdg deport vxfencoorddg

Create vxfendg on all systems :-

#echo “vxfencoorddg “ > /etc/vxfendg

Create vxfenmode on all systems :-

#cp /etc/vxfen.d/vxfenmode_scsi3_dmp /etc/vxfenmode

Start fensing driver on each system :-

#ls /sbin |grep vxfen
vxfen-shutdown vxfen-startup vxfenadm vxfenconfig vxfend

#/etc/init.d/vxfen start
Or
#/sbin/vxfen-startup

#haconf –dump -makero

Stop VCS :-

#hastop –all –force
Start VCS on each system:-

#hastartt

Display fencing membership and state information :-
#vxfenadm -d

See keys on the coordinator disk :-
#vxfenadm -i /dev/vx/rdsk/disk1

Read the existing keys on disks :-
#vxfenadm -s all -f /etc/vxfentab


************************FINISHED********************
SCSI3 persistent reservation :- it supports same storage to be accessed by :
1. different systems .
2. same system through different path.
3. It allows one system to access the storage at a time.