Virtualization Team

After installing or upgrading to VMware ESX 4, the Guest operating system’s memory usage might be overestimated on Intel systems that support EPT technology or AMD systems that support RVI technology. This issue might cause the memory alarms in vCenter to go off spuriously even if the guest is not actively accessing a lot of memory.

I have today visited another customer who had a problem that their virtual machines are always reporting a very high memory usage in vCenter while their OS task manager & TOP command in Linux machines were showing a very low memory usage. They did not face this problem before upgrading to vSphere which has made them unhappy with the upgrade. Fortunately, I was aware with this problem & was able to apply the magical VMware patch that has restored the customer happiness & confidence in VMware. The require VMware ESX 4.0 Patch was ESX400-200909401-BG: updates vmx and vmkernel64.

Many companies have always considered running Virtual Center in a virtual machine due to many advantages found below:

· Server Consolidation: instead of dedicating an entire physical server to VirtualCenter, you can run it in a virtual machine along with others on the same ESX Server host.
· Mobility: by encapsulating the VirtualCenter server in a virtual machine, you can transfer it from one host to another, enabling maintenance and other activities.
· Snapshots: A snapshot of the VirtualCenter virtual machine can be used for backup,
archiving, and other similar purposes.
· Availability: using VMware HA, you can provide high availability for the VirtualCenter server

One of the errors my customers repeatly complain about while upgrading to vCenter Server 4 or even when trying to install it from scratch is the following error:

“The DSN is pointing to an unsupported ODBC driver. Please re-configure your DSN to use one of the supported drivers.”

If you face this problem the first thing to do is to ensure that you are running a supported Database. Hint! Hint! SQL 2000 is no longer supported. If you are running SQL 2000 then you must upgrade to SQL 2005 or SQL 2008 before upgrading to vCenter Server 4.0

I know I have been pushing back my vSphere exam for a while due to the amount of projects I am working on this year. I have finally passed my exam two days back with a blazing score of 494(haha thought it would be quite lower than this, but I guess the elimination process of answers that does not make sense had worked out very well on this one). I would love to thank everyone in the VMware community who had posted tips for the VCP exam especially Kumaran, Brian, Scott Vessey.  As my return to the community I have decided to post some tips for the exam:

As most of you already know VMware Storage VMotion is the ability to live migrate a virtual machine from one storage to another without any downtime. The usage most IT Professional relate to VMware Storage VMotion is the following:

The ability to move your virtual machines from a storage or datastore to another for maintenance reason or storage replacement without downtime. Though I had just came to discover another reason where it became vital. Thanks to Vladan as he brought it to my attention when he commented on my previous post:  VMware ESX 4 Reclaiming Thin Provisioned disk Unused Space

Disk Thin Provisioning & its ease of use in VMware vSphere has been one of the most used features. Although Thin provisioning has allowed customers to avoid allocating space upfront & saved them tons of space, it does not unallocate space when files are deleted from the Virtual Machine, this is due to the way Windows & other operating systems handle file deletion.

In many cases, the customer will create a Thin Provisioned disk with 80GB & use 10 GB out of it. At this time that Virtual Machine will only use 10 GB on the ESX host. Few days later, he might require to use another 50GB for a temporary purpose. Now he will have the Virtual Machine using 60 GB on the ESX host. After few days he go and delete the files that is occupying the temporary 50GB, then he will discover that the virtual machine does not shrink as he delete files from it & he still has a 50GB of wasted space.

Don’t get me wrong. I am happy with the current VMware CEO as well the VMware team as over all. My post is more of a message to the VMware Team & specially the CEO. I believe this below tip can help VMware crush the competition, though they have to study it carefully as it require a brave decision.

Since VMware started & it has been successfully gliding of the nice waves. It has always lead the competition by the quality of its product, as well the essential feature that no one else had. Although no one else had succeeded on over come the reliability & performance of VMware yet, many of the essential features has been replicated in many other Virtualization products in the market. Nonetheless VMware has always been able to innovate new features that customers will desire, customers started thinking that they could wait a year more and get this feature in a cheaper product, which has enough features for their current setup. Yes, I will spell it out many are looking at Hyper-v in this manner.

Before I start with the article, I have to point out this is not a VMware bug. Its the VMware admins doing what they are not suppose to do. VMware ESX 3 & VMware ESX 4 Administration Guides mention clearly that you should not VMotion or Storage vMotion a Virtual machine before disconnecting it from CD Media & ISO images that is only available to the first host or Datastore. Actually it will even warn you when you trying to do that.

vSphere Virtual Center Linked Mode Prerequisites:

Well, yes this article has two headers or titles. Guess what they are almost identical.

I have seen “Error 28039. Setup cannot join vCenter Server to the linked mode group” all over the net & without any one posting resolution for it. hmmmm, how did I find out about this error and what made me looking for resolutions, well I had faced this same ugly error in my own lab. The resolution for it was nothing more than following the pre-requisite to vSphere Virtual Center Linked Mode which most people ignore. Below is the pre-requisite that you must follow for a successful installation of vCenter Linked mode & I will highligh the mostly missed one.
All the requirements for standalone vCenter Server systems apply to Linked Mode systems. In addition, to the following requirements:

Many of you have already heard about the new VMware vNetwork Distributed switch. It has been a really great innovation by VMware. I believe most of us has already learned something about its benefit like:

1- Simplify Virtual Machine Networking: As you get to create one switch per cluster & create the policy across all your ESX hosts at once instead of repeating the process endlessly.

2- Enhance Virtual Machine Networking:

• VMware vNetwork Distributed Switch maintains network runtime state for VMs as they move across multiple hosts, enabling inline monitoring and centralized firewall services.
• It provides a  framework for monitoring and maintaining the security of virtual machines as they move from physical server to physical server

If you don’t know what is VMware EVC or you need to find out more about it, please look at my last post VMware EVC enhanced VMotion Compatibility enable VMware VMotion across CPU generations

Ok, if you had read that and now wondering how to get it setup without having to shutdown your virtual machines. Then this small tip is for you.

As you know & I had mentioned that in my previous post on this topic that VMware will request you to shutdown all the virtual machines you have running on the cluster you want to enable VMware EVC for. To avoid having to shutdown your virtual machines what you can do is to create a temp cluster with few temp servers on it & VMotion your VMs to these servers. Enable VMWare EVC on your evacuated production cluster. Then again VMotion the Virtual Machines back to your original production cluster.

Everyone who had been using VMware for a while, would appreciate VMware VMotion. Actually VMware VMotion have always been a distinguished feature of VMware ESX servers. Despite of VMotion has always been a great feature, people using it at earlier stages used to have a tough time when having to use it across different CPU generation. That meant companies had to actually put similar hardware server in the same cluster, to guarantee that VMotion work smoothly. This was not possible at all the time, and was a tough call for implementers as they had to cheat masking manually in order to avoid VMotion not accepting to run between different CPU genrations.

It had been asked so often lately, if VMware vSphere support SRM & VMware View yet. I had even got calls from customers who tried to integrate the two together. The VMware statement is quite clear in this regard, both VMware Site Recovery Manager(SRM) & VMware View are not supported yet by VMWare vSphere 4.0. They will be supported by sometime in the 2nd half of this year. To check the support matrix & when its going to happen for most VMware product with vSphere, please check out the below document:

VMware vSphere 4.0 Software Compatibility Matrix