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The Oracle VM Manager Host NTP Requirements

The Oracle VM Manager Host NTP Requirements

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Download the Oracle VM Manager Installation Media
Oracle VM Manager Prerequisites
Install Oracle VM Manager
Oracle VM Manager Post Installation Checklist
 
Applicable for Oracle VM up to Release 3.2. Optional for Oracle VM Release 3.3 only if you do not have NTP services. 
With Oracle VM, accurate time is essential to maintain system stability due to time-sensitive cluster transactions between Oracle VM Manager and the Oracle VM Servers. Without accurate time, Oracle VM clusters can be brought to a complete standstill.
 
Up to Oracle VM Release 3.1.1, Oracle VM Servers that are discovered by Oracle VM Manager are configured to use the Oracle VM Manager host as the upstream NTP time source. Up to Oracle VM Release 3.1.1 the Oracle VM Manager hosts should have NTP installed and configured to synchronize with upstream Coordinated Universal Time (UTC) sources.
 
Oracle VM Release 3.2.x and above does not automatically configure NTP for the Oracle VM Servers or Oracle VM Manager. If you have two or more NTP servers, point your Oracle VM Servers to them using the Oracle VM Manager GUI via the Tools and Resources => NTP page.  
 
Up to Oracle VM Release 3.1.1, Upstream Coordinated Universal Time (UTC) sources should be configured for the Oracle VM Manager host using the /etc/ntp.conf file, and the Oracle VM Servers using Oracle VM Manager via the Tools and Resources => NTP page. 
 
The Network Time Protocol (NTP) is used to synchronize computer clocks over a network to a common timebase, usually UTC. UTC is the worlds primary time standard used to regulate clocks and time. There are numerous upstream public UTC time sources that allow the public to synchronize with them.
 
Oracle Linux and Red Hat Enterprise Linux ship with a default /etc/ntp.conf file that points to three of Red Hat's upstream public UTC time sources. A best practice is to have two internal NTP servers on your local network to provide time services for internal systems and devices. Using internal time servers normalizes system event time-stamps across the Enterprise as well as reduces NTP Internet bandwidth usage.

Oracle VM Manager Host NTP Configuration Roadmap:
1- Install NTP on the Oracle VM Manager host
2- Configure the upstream public UTC time sources
3- Disable the default "noquery" option for the Oracle VM Server Management network and restart the NTP service
4- Validate upstream synchronization by using the ntpq command
 
1- Install NTP on the Oracle VM Manager host
To validate if the NTP RPM is installed on the Oracle VM Manager host, as root, type "rpm -qa ntp".  
 
The next example shows the output from "rpm -qa ntp" on an Oracle VM Manager host with the NTP RPM installed.  
# rpm -qa ntp
ntp-4.2.4p8-2.el6.x86_64
 
If your Oracle VM Manager host is missing the NTP RPM, the NTP RPM is available at the Oracle Unbreakable Linux Network, the Oracle public yum repository and on the Oracle Linux media.
 
If your Oracle VM Manager host is registered with Oracle Unbreakable Linux Network, as root, type “up2date -i ntp” for Oracle Linux 5 systems, or “yum install ntp” for Oracle Linux 6 systems followed by "chkconfig ntpd on".
 
To install the NTP RPM from the Oracle public yum repository, for Oracle Linux 6 systems, as root type the following commands:
 
# cd /etc/yum.repos.d/
# wget http://public-yum.oracle.com/public-yum-ol6.repo
# yum install ntp
# chkconfig ntpd on
 
For Oracle Linux 5 systems, as root type the following commands:
 
# cd /etc/yum.repos.d/
# wget http://public-yum.oracle.com/public-yum-el5.repo
# yum install ntp
# chkconfig ntpd on
 
To install the NTP RPM from the Oracle Linux DVD or ISO file, as root, mount the DVD or ISO file, cd to the directory with the NTP rpm, and type “rpm -ivh ntp”.
 
The next example shows how to mount the Oracle Linux ISO file.
  • Download the Oracle Linux installation media (not source) from the Oracle Software Delivery Cloud - Oracle Linux and Oracle VM portal portal.
  • Copy the Oracle Linux installation media to a directory on the Oracle VM Manager host.
  • Log in to the Oracle VM Manager host as root, and unzip the file.
  • Mount the ISO file by typing “mount -o loop <FILE NAME>.iso /mnt”.
  • Change (cd) to the /mnt directory, i.e. “cd /mnt and type "find / -name ntp -print" to locate the RPM.
  • Change (cd) to the directory with the ntp rpm, and type “rpm -ivh ntp”.
  • Next, type "chkconfig ntpd on" to automatically start the NTP service when the host boots.
2- Configure the upstream public UTC time sources (Oracle VM Manager)
An Oracle VM Manager ntp.conf file should use two local NTP servers as the upstream UTC time sources. If the Oracle VM manager host is used as the upstream Coordinated Universal Time (UTC) source, disable the default "noquery" option for the Oracle VM Server Management network. Oracle VM Servers that are discovered by Oracle VM Manager 3.x up to 3.1.1 will be configured to use the Oracle VM Manager host as the NTP time host. 
 
The next example shows the default /etc/ntp.conf NTP servers settings for Oracle Linux and Red Hat Enterprise Linux.
 
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org
 
As root, edit the /etc/ntp.conf file and replace the Red Hat upstream public UTC time sources with your local NTP servers fully qualified domain names (FQDN) or IP addresses.
 
3- Disable the default "noquery" option for the Oracle VM Server Management network and restart the NTP service (Oracle VM Manager)
If the Oracle VM manager host is used as the upstream Coordinated Universal Time (UTC) source, disable the default "noquery" option for the Oracle VM Server Management network. 
 
Next, disable the default "noquery" option for the Oracle VM Server Management network. The next example shows the default /etc/ntp.conf "noquery" option.
 
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
 
Uncomment the line by removing "#", replace 192.168.1.0 with your Oracle VM Server Management network address, and replace 255.255.255.0 with the mask of your Oracle VM Server Management network.
 
Next, as root, restart the NTP server by typing "service ntpd restart".
 
# service ntpd restart
Shutting down ntpd:                                  [  OK  ]
Starting ntpd:                                            [  OK  ]
 
4- Validate upstream synchronization by using the ntpq command  (Oracle VM Manager and Oracle VM Servers)
Once the NTP service has been restarted, use the ntpq command to see the upstream servers with which the host is synchronized. ntpq -p lists the configured time servers, stratum, delay, poll, reach, offset and jitter values. For correct synchronization, the delay and offset values should be non-zero and the jitter value should be under 100.
 
As root, type "ntpq -p" as shown in the next example.  
 
# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================
+dns-pike.sf.mok 149.20.68.17     3 u   34   64  377    0.637   10.165   4.514
*ntp1.Rescomp.Be 128.32.206.55    3 u   61   64  377   28.341    5.549   4.854
 
Tip: An indication of improper synchronization is when the remote servers have jitter, delay and reach values of 0.
 
NTP Troubleshooting (Oracle VM Manager and Oracle VM Servers)
  • NTP uses UDP port 123. If iptables is enabled on the Oracle VM Manager host, ensure that UDP port 123 is open.
  • NTP clients, i.e. Oracle VM Servers will only synchronize with upstream servers with a lower than 16 stratum. Once Oracle VM Servers are discovered by Oracle VM Manager, there will be several minute delay before synchronizing with the Oracle VM Manager host.
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