Ok, this is a difficult issue to summarize and put into a VMware foum post but I'll try my best 
Friday, April 9th, around midnight, we starting receiving calls from our operations team that everything was running slow and sluggish. After the network team couldn't determine any issues early into Saturday morning, the VM and storage admins were called in. To make a long story short, everything on our fiber channel storage (All our VM hosts and several physical hosts) were a mess. After Brocade looking at our logs, there were no major events on the storage side. So.. digging further around the time we started hearing complains, we only came up with two things:
I will attach images of these events:
1 - This is the change log from Netapp SANscreen showing that the Qlogic HBA driver was updated. We have not made any ESX or Vcenter changes or installed any upgrade for at least 30 days! What is going on here?
2 - This is from the vcenter events showing that a "Upgrade VirtualCenter Agent" was upgraded automatically. After that occurred, we lost connection to all hosts. How could this happen and how can you disable those jobs?
In the end, after scrambling around looking for answers, Saturday April 10th at 1:30pm, things started performing normally again. We didn't make any changes during this time. A very strange and frustrating chain of events. Any insights?
