Potential issues running with RHEL 7.4 or CentOS 7.4

Problem:

We have had reports of customers experiencing the following issues when running with RHEL 7.4 or CentOS 7.4, or earlier 7.x versions that have updated NFS packages:

• Zeneventserver times out and/or crashes

• Deletion of files takes a very long time from the /opt/serviced/var/volumes/<instanced id>/zeneventserver/index directory

• Upgrade of serviced fails

Remediation:

Edit to nfsmount.conf (Defaultvers=4.0)

While we are still investigating the root cause, there may be a defect with file locking when using NFS 4.1 with RHEL or CentOS 7.x. Customers using RHEL/CentOS 7.x should force the use of NFS to 4.0, as we've seen positive results doing this to affected users. To do this, follow these steps:

• Edit /etc/nfsmount.conf on each host
• Find the following line:
  # Defaultvers=4
• Uncomment it and change it so that it looks like:
  Defaultvers=4.0
• Save that file
• Stop Resource Manager and serviced on all of their hosts where NFS is mounted
• On each host, issue: systemctl restart nfs-server
• Bring serviced back up and start resource manager
• Once the nfs shares are remounted, verify that NFS mounts are using NFS version 4.0 by running: nfsstat -m on the delegates in the RM pool
  

  [root@delegate1 ~]# nfsstat -m
  /opt/serviced/var/volumes/afwdlj8lpc6n6fk3rojbfq7lt from 10.10.123.123:/serviced_volumes_v2/afwdlj8lpc6n6fk3rojbfq7lt
  Flags:
  rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.10.123.124,local_lock=none,addr=10.10.123.123

Edit to lvm.conf (units="h")

RHEL/CentOS 7.4 changes the LVM configuration (in /etc/lvm/lvm.conf) to use units="r", which causes LVM commands to output sizes as human-(r)eadable with '<' rounding indicator. This rounding indicator causes a parsing error in the serviced pre-upgrade script. 

The fix for this is straightforward:

• Edit /etc/lvm/lvm.conf on each host
  • Find the following line:
    units="r"
  • Change it to read:
    units="h"
  • Save that file
• (NOTE: you do not have to restart LVM to make these changes take effect)
• To confirm that LVM is now using the correct units
  • run the command lvmconfig | grep units on each host:
    [root@delegate1 ~]# lvmconfig | grep units
    units="h"
  • run the pvs, vgs, and lvs commands on each host, and confirm you do not see any rounding symbols (such as <) in the sizes shown