Solved

NTP Time In AHV And CVM is not Synchronizing

  • 12 March 2020
  • 7 replies
  • 273 views

Badge +1

I am having an External NTP server, Which is tagged to my CVM, unfortunately my AHV is not corresponding with mt NTP server even it is reachable from my hypervisor level. I have checked my Hypervisor thru ssh and run the command ‘date’ its gives me different time from my NTP server.

icon

Best answer by HITESH0801 12 March 2020, 08:37

View original

This topic has been closed for comments

7 replies

Userlevel 4
Badge +2

Hey @CarloNX 

Did you take a look at the NTP troubleshooting article?

https://support-portal.nutanix.com/#/page/kbs/details?targetId=kA032000000bmjeCAA

See if this article helps you.

 

Regards,

Shaurya Bhardwaj

Badge +1

Oh hi there thanks!
i just opened a support and found out that my NTP server is using its local time, i think i just need to configure my NTP server to synchronize with reliable time source. Thanks again! :) 

Userlevel 4
Badge +5

Hello @CarloNX 

Glad that the problem was isolated. 

You can use the following document to configure NTP in Prism and know the guidelines and best practises of configuring NTP.

 

NTP Server Guide 

 

Badge +1

Hello @HITESH0801 ,

I have a question, If the Nutanix cluster is connected directly to External Time Source(Public NTP server),  What will happen if the the Internet suddenly went down? Does it affects my CVM,Hypervisor, and VM’s?

 

Thank you! 

Userlevel 4
Badge +5

Hello @CarloNX 

If the sync with an external NTP server is broken, there are chances of time-drift. 

The following NCC Health check will FAIL if there is a time drift or some issue with NTP.

NCC Health Check: check_ntp

The following KB mentions the impact of the check failure on the environment 


NCC Health Check: check NTP KB 

Badge +1

hello @HITESH0801,

Thanks! Well appreciated

 

regards,

Userlevel 3
Badge +4

@CarloNX I thought I might add a bit of info, as you asked specifically “Does it affects my CVM,Hypervisor, and VM’s?” 

If you look at CVM time synchronization across the cluster, i.e. “allssh ntpq -pn” you’ll see that one CVM is set to sync from outside the cluster and all other CVMs will sync to this CVM. So long as CVMs are in sync with eachother there should not be a disruption to data service but some impact could be seen. 

As you likely know, any domain authentication using Kerberos can only suffer a 5 minute time discrepancy, so if CVM time drifted 5+ minutes from AD server time, LDAP authentication with the AD domain would fail. This is particularly troublesome if using a Hyper-V cluster and Kerberos authentication is configured for file access. In that case failing authentication could cause data service disruption. This is one reason I always recommended to sync to the same sources as your AD domain controller.

Significant time discrepancy between the CVM cluster and Prism Central, or between different CVM clusters which are paired as remote sites for Async DR replication can also cause some issues, but impact would be isolated cluster management from Prism Central, or in the case of the remote site setup you could see issue with remote replication or DR operations. In either case, local operation of the cluster is not impacted but sync relationships with the remote system could be impacted.

If the CVM time runs ahead, you can work with Nutanix support to correct the time discrepancy.