Virtualization Team

Till today everywhere I looked recommended using RDM over VMFS for performance (when a higher I/O is required), though today while studying for my VMware Design Exam I have got my hand on the “ Performance Characterization of VMFS and RDM Using a SAN” document by VMware. The interesting executive summary of the document is copied up to the letter below:

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Executive Summary:

The main conclusions that can be drawn from the tests described in this study are:

• For random reads and writes, VMFS and RDM yield a similar number of I/O operations per second.

I have earlier mentioned on my blog that I will publish my study guide for VMware Enterprise Administration Exam, but as I have been preparing for my design exam & killed with projects at work. I really had no time to put it all online. Further, it seems these exams are expiring soon. For that I have decided to only publish the most ignored chapters required for the VMware Enterprise Administration exam & VMware Design Exam. I will start with NPIV. When I was preparing for my exam beside the Exam blueprint NPIV was not covered in any study guide including the DSA materials. As I did not use it much in real life I had got a bit of exposure and note taken while reading the chapter about it in the Fibre Channel SAN Configuration Guide which should be almost of sufficient knowledge for both VMware Enterprise Administration Exam & VMware Design Exam as I assume at least. Below are my note of NPIV.

While preparing for my VMware Design Exam, I have stumbled upon this great pdf that document VMware ESX & ESXi connections & ports in details. It even cover the connections & ports for VMware additional components like VMware Update Manager & vCenter Converter.  Although many documents do the same, what got my attention is all this are fitted into one detailed compact image. I though this document will be useful for many others planning to take the exam, or even Virtualization Experts who just want to design their network & adopt for the ports they need to open through firewall. Below is a small foot print of the image. To download the document just hit on the image below.

I have scheduled my VMware VCDX Enterprise Administration Exam on the 1st of June 2010. I was planning to take 10 days off work before the exam for preparation, but I got stuck at a large project which has minimized my study time including travel to 5 days.

I am not sure how many people has heard of VMware Long Distance VMotion, although the concept has been supported since fourth quarter of last year. For that, I thought its worth getting people to know about it. It even get more important when deciding on your cloud computing vendor.

At the moment, many companies offer some form of cloud computing services. Some of these cloud services are really nice, specially the one built on VMware Technology. Features like Memory Page Sharing, Memory Over Commitment, VMotion, Storage VMotion, HA, SRM, Snapshot, VMware Data Recovery & so on has made VMware one of the best platforms if not the best for cloud computing. These features has helped cloud computing vendors to offer a highly available & flexible solution for lower cost.

I know I am late on this one, but as many of you have noticed I have not got a chance to blog much lately. As I have been traveling for training between London & Budapest with a very limited internet access & a very busy schedule for the past month. I am actually still in Budapest at the moment, but I thought I must Congrats all the 2010 vExperts announced by VMware last week. I would like to thank every one who has helped vExpert award to continue in 2010 (Specially John Troyer).

I am sure many of you have been looking for a comprehensive comparison between VMware ESX 4.0 & MS Windows Server 2008 R2 Hyper-V.  I am sure you have found plenty of them with one problem they all were mostly sponsored by one of the vendors. Many of us were ready for a real independent comparison. If you were, then I have a great news for you. ITComparison.com has just released an updated version of their famous Hyper-V & VMware comparison. If you are in a rush just go and check it out at: VMware ESX 4.0 vs MS Hyper-V R2.

In order to improve VMware Snapshots  & enhance them further, VMware has just published a Snapshot feedback to its users. The return of the feedback will be used to guide future development of VMware Snapshots & enhance it depending on your feedback. If you believe VMware Snapshot technology is in need for any enhancement its the time for you to get your voice heard. I have just filled my VMware Snapshots feedback, so file yours now . Below is the link to the feedback forum:

The URL to this survey is:  http://www.surveymethods.com/EndUser.aspx?B094F8E2B1F2E0E6B6

Thanks to Duncan Epping, as I have got the above info on his blog at: http://www.yellow-bricks.com/2010/04/13/feedback-on-vmware-snapshots/ & thought its worth sharing to help VMware improve its snapshots. So please take your shot at it. It will not take you more than 15 minutes.

As many of my customers are still on VMware ESX4 & not yet upgraded to ESX4U1, I get many complains about virtual machine console timeout error from web access for non administrator users. Yeah, I have already pushed an upgrade recommendation, but as usual most companies take more time approving the change request than to carry out the change. If you have VMware ESX4U1 & you are facing a problem & hit this page, then please ignore this post as this bug was fixed in update 1. If you want to read the VMware KB on this issue you should check out:

Accessing the console of a Windows virtual machine through Web Access in ESX 4.0 times out

I am sorry if this is too obvious for some of you, but it seems not obvious to most of my customers. Every few days I get the following question from my customers, which I will try to briefly answer in this post.

Where can I find vmware vCenter converter in VMware vCenter 4?

Unfortunately, unlike most other VMware feature the VMware vCenter Converter does not have any obvious shortcut in vCenter.  To start vCenter converter in Virtual Center you will need to follow the below steps:

1. Make sure you are in host & clusters view.
2. Choose one of your hosts or clusters in vCenter
3. From the top drop down menu choose one of the following paths depend on if you have chosen a host or cluster in step 2.

VMware ESX host can disconnect from VirtualCenter & have a problem connecting to it again for many reasons. Below I will cover few ways to diagnose the problem, few common resolutions to this issue.

In these cases usually the first thing you want to do is to log on through ssh, vcli, or directly on the server console & check the following log files for errors:

Vmkernel – /var/log/vmkernel
Vmkernel Warnings – /var/log/vmkwarning
ESX Server host agent log – /var/log/vmware/hostd.log
Service Console – /var/log/messages
VirtualCenter agent – /var/log/vmware/vpx

Note: it would be great if you get to know what each of the above log files is for.  VMwareWolf has a great post explaining these log files that can be found at: http://www.vmwarewolf.com/which-esx-log-file/

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

As a start don’t let the title fool you this is not related only to Microsoft virtualization, but to every virtualization platform out there. Don’t let vendors mislead you as the saving can be higher on Microsoft Licenses with non Microsoft Hyper-visor like VMware where you can put more virtual machines on the same hardware box. Ok, so clearing the confusion out of the way read below to find out what I am talking about.

Being on the consulting role, I get to meet customers everyday on all levels (Administrators, Managers, CEOs,  Directors, Business). When they ask our advice on consolidating their enviornment & I bring the idea of virtualization one question I get hammared with every time ” How would paying for virtualization licensing is going to save us money?”.  Below are some of our & yours traditional answers & how a stubrn customer will reply to it: