In my article about creating an Azure virtual machine, I walked us through the very basic wizard to create a VM. There is an entire segment of the virtual machine build process dedicated to optional features. These features allow new virtual machines to integrate a VM into an existing Azure environment. When we created our first machine we accepted the default settings, which created new network and storage accounts. That works perfectly for a first look but it wouldn’t be appropriate for use in a real life Azure Infrastructure.
Fibre channel storage is great because it mostly “just works”. You provision storage, assign it to the WWPNs, rescan the adapters, and the luns are presented. There isn’t a lot of configuration in the GUI and, honestly, it can be hard to detect link speed or even if a link is up. In the Storage Adapter tab you can see if a path is down, but how do you detect the link speed?
After performing an upgrade from ESXi 4.1/ESXi 5.0 to ESXi 5.5 u2 I noticed increased latency events on hosts. More troubling, the affected hosts were frequently dropping all presented datastores, though they would reconnect within a few seconds. The events may appear in your event log as below: While there are many possible causes to explore these sorts of connectivity issues, one that is often overlooked is how ESXi heartbeating to the datastores.