RH5 two node cluster qdisk hung 20 more seconds

Hello ,
We are running two node RH5 iscsi cluster on Dell equal logic array , more info mentioned below

Version: 6.2.0
Config Version: 31
Cluster Name: itlabptscl
Cluster Id: 44574
Cluster Member: Yes
Cluster Generation: 632
Membership state: Cluster-Member
Nodes: 2
Expected votes: 3
Total votes: 2
Node votes: 1
Quorum: 2
Active subsystems: 9
Flags: Dirty
Ports Bound: 0 11 177
Node name: itlabpts01-priv
Node ID: 2
Multicast addresses: 239.192.174.204
Node addresses: 10.0.0.10

Issue- we are frequently getting qdisk hung message
quorum disk /qdiskd hung for 20 seconds on active node and due which cluster services went down and fenced the node
How to fix qdisk hung issue permanently ? And what is root cause of qdisk hung ?

we are running cman version "cman-2.0.115-85.el5"

qdiskd[32010]: qdiskd: read (system call) has hung for 20 seconds
qdiskd[32010]: In 20 more seconds, we will be evicted
qdiskd[32010]: cman_dispatch: Host is down
qdiskd[32010]: Halting qdisk operations
qdiskd[11314]: Quorum Partition: /dev/dm-4 Label: pogda_qdisk
qdiskd[11315]: Quorum Daemon Initializing
qdiskd[11315]: Heuristic: '/bin/ping -c3 -t2 10.218.16.126' UP

Thanks in advance !

--Subodh Bagade