Esxi host not responding state

[VPXA]

Hi All,

Looking for your valid suggestions on below summary.

we have received multiple "host not responding" alarms from the hosts in one Data Center, happened for only 1 min and the connection restored.

Error Messages from Events :

1. Can not syncronize host, Failed to Sync with vCenter agent on the host

2. triggered by event 249004607 Host is not responding.

did not find much events for this, please suggest for the cause.

at the same time backups are running 

[birend1988]

Is your backup and management are on same network?

If this is happening only at the time of backup, you can go ahead and increased the time out setting for host not responding.

https://kb.vmware.com/s/article/1005757

Hope this will resolve your issue.

[Srijithk]

This could have happened due to host sync failures

what is Host-sync?

Host-sync is a mechanism used by vCenter Server for fetching incremental changes to objects residing on an ESXi host, such as Host Configuration, Virtual Machine, Datastore etc. This is done that so state maintained and persisted by vCenter Server (vpxd) is always up-to-date with the state on the host. Typically, an operation happening in vpxd (e.g. powering on a VM) dispatches the call to host for execution, waits for it complete and then triggers a host-sync. The expectation is that all the changes that may have been caused by this operation will be fetched and processed in vpxd when this host-sync finished. Changes on the host may also happen without an explicit user-operation, such as changes to free-space on the datastore, change in power state of a VM etc. They too trigger a host-sync. 

Vpxd and vpxa work together to determine when a host-sync needs to happen 

vpxd makes a remote call to vpxa to gather up incremental change and vpxd processes these changes to update its state 

ssh to vc

cd var/log/vmware/vpxd

view the vpxd.log for any missed heartbeats for that host

you can proactively perform the workaround in https://kb.vmware.com/s/article/1005757

Thanks,

Srijith