Thursday, July 25, 2013

Simulating HA/FDM Failover on vSphere

While working on cases I got this question so many times before so thought to just write few words about it.

How to simulate HA/FDM in vSphere environment and check the functionality of HA/FDM and other settings or the VMs.

Based on the version of vSphere you are running you can simulate HA/FDM in few ways.

1st Method

For  4.x environment where you are running HA based on AAM and have two redundant NICs for the Management Network vmkernel (if ESXi) /Service Console (if ESX) then you can just track down the uplink switch ports and issue the command manually on the switch to shut down the corrsponding port or just plug out the cable on the back of the physical ESX/ESXi host which will disconnect the Management Network/Service Console of the host.

2nd Method

For 5.x it uses FDM where not only Network Heartbeat used but also the Storage Heartbeat is used before the Cluster declares the Host as Isolated and work on the Isolation Response set.

In our example we have only Two ESX/ESXi hosts with two Uplinks configured and using only one Shared Datastore.

So first you need to configure at the Cluster level to set the datastore heartbeat to None. No datastore is used for Storage Heartbeat.

Now for the Management Network you can either remove the cable from the back of the ESXi host or shut down the uplink switch Port/s.

Once the Network got disconnected, the HA Cluster will wait for the default settings and then once the time out is over it will declare the host as isolated. and work on the Isolation Response configured for the VMs (Default is Leave VMs power on) and probably restart the VMs on the other surviving host. Now we are not getting in to the details about the resources available or capacity to hold the VMs.

3rd Method

To disconnect the network is an option while the host keep running so if you have the ability you can actually shut down the Host by powering off physically or by using any 3rd party KVM, DRAC, iLO, RAS alike utilities.

4th Method

Now this last method may/may not work which is involving unloading the modules of Network Driver and Storage Driver but indepth knowledge is required to find and unload/load them. Depending on the components used and the version/s of ESX/ESXi, the command/s may vary.

If you feel any information required to be added/modified then please leave the comment and I will update the post.

Thanks for your time.

Share and Care !!

No comments:

Post a Comment