VMware ESXi 5.5 host not responding

We have a few hosts that we keep loosing contact with vCenter although the VM's keep running and the console on the host is accessible although the restart command fails but if a forced restart is performed the host is accessible for a while. When the host is inaccessible it is still pingable and the host holding webpage is still visible but it cannot be accessed by vCenter of vSphere Client

We had the issue when running under ESXi 5.1 so performed a clean fresh install on all the hosts of ESXi 5.5 to see if that would resolve the issue which sadly it hasn't.

The only other thing we have running in this environment id Veeam 7.0 backup
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
vCenter Server is just a management server, it performs no functions, so there will be no impact on the VMs.

Are you running the very latest ESXi 5.5 update ? e.g. Build 2718055 ESXi 5.5 Patch 5, if not apply it.

Is vCenter Server virtual or physical ?

is it all hosts, or some hosts? what is similar ?

If you perform pings between vCenter Server and FQDN (IP Address) constantly, do any timeout....?

when this issues occurs ?
andrew_2706Author Commented:
Yes 5.5 is up to date running 2718055

vCenter is a on a VM

It affects all the hosts which are of different manufacturer so nothing in common there and they are running their respective custom build of ESXi

Ping is unaffected to or from any machine.

We haven't identified any particular time when this occurs
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
vCenter does have a VMXNET3 interface.

So you have test results, with a common ping, to ALL hosts from vCenter and another workstation to all your hosts, when this issue occurs.

What do you observe, in vCenter?

disconnected, not responding ?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
could you also explain "although the restart command fails" ?

 forced restart is performed the host is accessible for a while. ?

if you had this both with ESXi 5.1 and now 5.5, it would seem it's environment related ?

network switches ?

are you using iSCSI storage ?

but it seems like the Agent is going into a hung state....
andrew_2706Author Commented:
In vCenter to the right of the host it says (not responding)
at the side of the VM's you get (disconnected)

On the console if you login and select restart the host fails to restart so it has to be hard restart and yes the host is accessible for while even at times a few days.

Yes we're using iSCSI for the storage.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Okay, so something is seriously not responding, and is hung/crashed.

There are no missing iSCSI paths, datastores, or constant polling.

and the iSCSI SAN is on the HCL ?
Mr TorturSystem EngineerCommented:
if this is on all ESXi i would say too that it comes from switches or San.. or vcenter vm if you did not recreated or migrated it when you upgrade from 5.1 to 5.5.
Mr TorturSystem EngineerCommented:
Andrew_2706 do you know when your issue start ? and what have been done just before...
andrew_2706Author Commented:
I've not managed to make any progress with this so going to close this

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andrew_2706Author Commented:
No progress on this so closing it
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