Gabe asked the question on one of my recent posts if it made sense to enable Hot-Add by default and if there was an impact/overhead? Lets answer the impact/overhead portion first, yes there is an overhead. It is in the range of percents. You might ask yourself where this overhead is coming from and if that is vSphere overhead or… [...]
I was listening to some VMworld talks during the weekend and something caught my attention which I hadn’t realized before. The talk I was listening to was VSP2122″VMware vMotion in vSphere 5.0, Architecture and Performance”. Now this probably doesn’t apply to most of the people reading this so let me set the scenario first: Different hosts from a CPU/Memory perspective [...]
I was just checking out some of the VMworld Sessions and one that I really enjoyed was the one on “Memory Virtualization” session by Kit Colbert and YP Chien (#VSP2447). This session has a lot of nuggets but something I wanted to share is this script that YP Chien / Kingston showed up on stage. This script basically shows you [...]
Before we dive in to it, lets spell out the actual name of the feature “Swap to host cache”. Remember that, swap to host cache! I’ve seen multiple people mentioning this feature and saw William posting a hack on how to fool vSphere (feature is part of vSphere 5 to be clear) into thinking it has access to SSD disks [...]
This question has come up several times over the last couple of weeks so I figured it was time to dedicate an article to it. People have always been used to monitoring memory usage in a specific way. This always worked fine until ESX(i) 3.5 introduced the aggressive usage of Large Pages. In the 3.5 timeframe that only worked for [...]
Back in the days when Servers still had 8GB or 16GB memory at most a setting was introduced that guaranteed the hypervisor had a certain amount of free memory to its disposal. The main purpose of this being of course stability of the system. As with any Operating System free memory is desirable to ensure it is available whenever a [...]
Frank and I have discussed this topic multiple times and it was briefly mentioned in Frank’s excellent series about over-sizing virtual machines; Zero Pages, TPS and the impact of a boot-storm. Pre-vSphere 4.1 we have seen it all happen, a host fails and multiple VMs need to be restarted. Temporary contention exists as it could take up to 60 minutes [...]
