I have 4 servers on the VirtualBox. Two of the servers are a CentOS 7 cluster with Pacemaker(corosync), and they have an NFSv4 server in Active/Passive mode. There are also 2 clients with CentOS 6, also using this NFS server.The problem does not always occur, but sometimes when I manually or automatically failover from the active NFS server cluster, both clients give the error: Permission denied. The tcpdump from the clients shows:  [17:24:29.271467] IP client.example.net.34236755563 > server.example.net.nfs 112 getattr [|nfs][17:24:29.271619] IP server.example.net.nfs > client.example.net.3423675563: reply ERR 24: Auth Bogus Credentials (seal broken)Until this problem is solved nothing is working: I have tried to transfer to NFSv3, tried different cluster configurations, tried a grace period for NFSv4 from 10 to 90 seconds, with no luck. Cluster configuration:node 1: storage1node 2: storage2primitive p_drbd_nfs ocf:linbit:drbd \    params drbd_resource=cgp \    op monitor interval=31s role=Master \    op monitor interval=29s role=Slave \    op start interval=0 timeout=240s \    op stop interval=0 timeout=120sprimitive p_fs_home Filesystem \    params device=/dev/drbd0 directory=/mnt fstype=xfs options=noatime,nobarrier \    op monitor interval=10s \    meta is-managed=trueprimitive p_ip_nfs IPaddr2 \    params ip=192.168.56.100 cidr_netmask=24 \    op monitor interval=30s \    meta is-managed=trueprimitive p_nfs_exports exportfs \    params fsid=0 directory=/mnt options=rw,async,no_wdelay,mountpoint,insecure,no_subtree_check,no_root_squash clientspec=192.168.56.0/255.255.255.0 wait_for_leasetime_on_stop=true rmtab_backup=none \    op monitor interval=10s \    op stop interval=0 timeout=120s \    meta is-managed=trueprimitive p_nfsserver nfsserver \    params grace_time=90 proc_num=16 \    op monitor interval=30s \    meta is-managed=trueprimitive p_ping ocf:pacemaker:ping \    params host_list=192.168.56.1 multiplier=1000 attempts=1 timeout=3 name=p_ping \    op monitor interval=5 timeout=60ms ms_drbd_nfs p_drbd_nfs \    meta master-max=1 master-node-max=1 clone-max=2 clone-node-max=1 notify=true is-managed=trueclone cl_p_ping p_ping \    meta is-managed=true target-role=Startedlocation l_0 ms_drbd_nfs \    rule $role=Master -inf: not_defined p_ping or p_ping lte 0colocation c_1 inf: p_fs_home ms_drbd_nfs:Mastercolocation c_2 inf: p_nfsserver p_fs_homecolocation c_3 inf: p_nfs_exports p_nfsservercolocation c_4 inf: p_ip_nfs p_nfs_exportsorder o_1 inf: ms_drbd_nfs:promote p_fs_home:startorder o_2 inf: p_fs_home p_nfsserverorder o_3 inf: p_nfsserver p_nfs_exportsorder o_4 inf: p_nfs_exports p_ip_nfsproperty cib-bootstrap-options: \    dc-version=1.1.10-32.el7_0.1-368c726 \    cluster-infrastructure=corosync \    stonith-enabled=false \    no-quorum-policy=ignore \    last-lrm-refresh=1428329105rsc_defaults rsc-options: \    resource-stickiness=200Here is a string from the client fstab file:192.168.56.100:/        /mnt                    nfs     nfsvers=4,proto=tcp,rsize=32768,wsize=32768,hard,timeo=300,retrans=2,bg,actimeo=3,noatime,nodiratime        0 0
Clustered NFS server reply ERR 24: Auth Bogus Credentials (seal broken)
centos;mount;nfs;cluster;pacemaker