Virtualization

One of my most frequently read articles is on how to use MBRAlign to align your virtual machine disks on Netapp storage. Well, after Netapp has released their new Virtual Storage Console (VSC4) the tedious task of using MBRAlign might be eased for some admins. Optimization and Migration The new VSC4 console for vSphere has a new tab called Optimization and Migration. Here you are able to scan all or some of your datastores to check the alignment of your virtual machines. The scan manager can even be set on a schedule so that changes to the datastore will be recognized. ...

If you’ve built a virtual infrastructure you’ve probably had to decide whether or not to use Beacon Probing when setting up your vSwitch uplink ports. But what is it, and why do we need it? Let me propose a scenario. Assume that we have a virtual switch with three uplinks, and one of those uplinks fails. If the uplinks are setup correctly, they will see the failed uplink and start sending their frames over the other active uplinks. This is standard network fault tolerance from vSphere. ...

VMware has lots of ways to setup networking on their ESXi hosts. In order to set this up in the best way for your needs, it’s important to understand how the traffic will be routed between VMs, virtual switches, physical switches and physical network adapters. Before looking at an example, we should review some networking 101. Machines on the same vlan on the same switch can communicate with one another (assuming there is no firewall type devices in the way). Machines on different vlans on the same switch cannot communicate unless the traffic passes through a router. ...

It’s important to understand how VMware ESXi servers handle connections to their associated storage arrays. If we look specifically with fibre channel fabrics, we have several multipathing options to be considered. There are three path selection policy (PSP) plugins that VMware uses natively to determine the I/O channel that data will travel over to the storage device. Fixed Path Most Recently Used (MRU) Round Robin (RR) Let’s look at some examples of the three PSPs we’ve mentioned and how they behave. The definitions come from the vSphere 5 storage guide found below. ...

Emulation and Virtualization are not the same thing. In many cases you’ll hear them used interchangeably but they are different concepts. Emulation Emulation consists of taking the properties of one system and trying to reproduce it with a different type of system. When it comes to computers, you may have seen some software emulators that you can install and run on a PC or MAC, that will reproduce the characteristics of an older system such as a Nintendo or other gaming console. As an example you could then perhaps run Super Mario Bros. on your work desktop (I am not advocating the playing of video games at work). In this case the software emulator is mimicking the gaming console so that the game could be run inside the emulator, even though the underlying hardware is an x86 architecture. ...

Many storage providers have been working with VMware to improve performance of disks by giving VMware access to invoke capabilities of the storage system. There are basically three main primitives that VMware can invoke to do this. Full Copy Hardware Assisted Locking Block Zeroing Full Copy Lets look at what happens when you clone a VM without VAAI. The ESXi server will start to copy the blocks of the original VM and start to paste them in the new location. Below is an animation to describe this process. ...

vSphere has made it very simple to resize disks. They old days of finding larger disks to put in your severs and cloning or migrating data aren’t necessary now that virtualization has become widely used. If you’re using vSphere you can easily extend non system drives by changing the size of the Hard Disk, and then going into the virtual machine and using diskpart or Disk Manager and extending the drive. ...

I found people have a hard time understanding that a SAN Snapshot and a VMware snapshot are fundamentally different. I think because unless you’re a storage administrator, you’re probably not dealing a whole lot with snaps to begin with. VMware has made it more commonplace for System Administrators to deal with snapshot technology. SAN Snapshots Lets first look at how traditional SANs take snapshots. To start we have 6 blocks being used. The file system has marked blocks which blocks are being used. ...

VMworld 2011 was held at the Venetian Hotel in Las Vegas. Over 25,000 attendees this year. It was held in Las Vegas, but the sites and attractions didn’t take away from the event. Despite all the distractions that Las Vegas can provide, there was too much going on at VMworld to get caught up in the city. My favorite part of VMworld was the Hands on Labs. After signing up for the specific lab you wanted, you were ushered to your assigned desk. There were dual screen workstations setup at every desk and very straight forward instructions on how to complete the labs. These labs would get very in depth and would show you why and what was happening behind the scenes when you would perform your operations. I especially enjoyed the Netapp lab. ...