While there are many new changes in VMWare ESXi 5.0, like Image Builder, Auto Deploy/Central Management, Firewall Changes, USB 3 Support and hardware upgrades, Today I’m going to highlight Cluster HA.
In vCenter 5.0 VMware Cluster HA functionality has been fully revamped. The clunky Automated Availability Manager (AAM) used in 4.X and below is now replaced by Fault Domain Manager (FDM). AAM had many quirks and limitations some of them being that it only used the management interface as the heartbeat communication for nodes in the cluster. Troubleshooting it when it broke was a headache because it wrote too many log files all over the place. AAM could also only have 5 cluster masters which were elected when the first 5 ESXi hosts joined the cluster, this could not be exceeded and if the hosts needed to change it had to be done manually via configuration files. This caveat would need to be taken into consideration in your infrastructure design so that all of the masters didn’t reside in the same enclosure, DC, running of the same power, etc…
FDM is far more resilient to host failures and isolations. It has a new cluster master election process which assigns a single node as the cluster master; if that node dies any node inside cluster can rerun the election process and assign a new master inside the cluster. If host isolation occurs the isolated hosts can function on their own and elect a new master. Once the hosts can communicate with one another and there are multiple masters present in the cluster the election process will begin and a single master will be elected once again. FDM now uses the management interfaces as a heartbeat but also the storage network (datastore) for heart beat communication. If you bring down your management switches for your ESXi servers for maintenance/failure the cluster can still communicate on the storage network not causing any re-election inside the cluster or any sort of freak out. FDM also has a single log file (/var/log/fdm.log) for troubleshooting and supports syslog for centralized log gathering and possible monitoring functionality. FDM is exciting news for VMware admins and end users alike!
I hope that you find the write ups on cluster HA and vCenter Storage helpful. If you’d like more information on any new vCenter features please comment below.
