Microsoft SQL Server on VMware vSphere Availability and Recovery Options

VMware
Running Microsoft SQL Server on VMware vSphere offers many options for database availability and disaster recovery utilizing the best features from both VMware and Microsoft. For example, VMware vSphere vMotion and VMware vSphere Distributed Resource Scheduler (DRS) can help to reduce planned downtime and balance workloads dynamically, and VMware vSphere High Availability (HA) can help to recover SQL Server databases in the case of host failure. At the application level, all SQL Server features and techniques are supported on vSphere, including AlwaysOn Availability Groups, AlwaysOn Failover Cluster Instances, database mirroring, and log shipping. SQL Server availability features can be used inside of a virtual machine just as you would on a physical server, and combined with vSphere features to support flexible availability and recovery scenarios, applying the most efficient and appropriate tools for different use cases.   AlwaysOn is a…
Read More

Slight change in “restart” behavior for HA with vSphere 5.0 Update 1

VMware
Although this is a corner case scenario I did wanted to discuss it to make sure people are aware of this change. Prior to vSphere 5.0 Update 1 a virtual machine would be restarted by HA when the master had detected that the state of the virtual machine had changed compared to the “protectedlist” file. In other words, a master would filter the VMs it thinks had failed before trying to restart any. Prior to Update 1, a master used the protection state it read from the protectedlist. If the master did not know the on-disk protection state for the VM, the master did not try to restart it. Keep in mind that only one master can open the protectedList file in exclusive mode. In Update 1 this logic has…
Read More

vSphere 5.0 HA restarting of VMs with no access to storage?

VMware
I had a question today around the restart of VMs with no access to storage by HA. The question was if HA would try to restart the VM and time out after 5 times. With the follow up question, if HA would try again when the storage would return for duty. By default HA will try to restart a VM up to 5 times in roughly 30 minutes. If the master does not exceed it will stop trying. On top of that HA manages a “compatibility list”. This list will contain the details around which VM can be restarted and where. In other words; which hosts have access to the datastores and network portgroup required for this VM to successfully power-on. Now if for whatever reason there are no compatible…
Read More