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vCenter MAC Address allocation and conflicts

Fridays in the Xtravirt office offers a time for consultants to gather round and have a great chinwag about whats been going on for them in the week and, more importantly, ask questions and get answers! Something raised this week was the allocation of MAC addresses to virtual machines. If you have multiple vCenter instances creating virtual machines, how can you guarantee that you wont get conflicts generated? It’s an interesting question and the answer is documented; but you may not already know the answer.

When a vCenter server is installed a unique ID is generated. This ID is randomly generated and is in the range of 0 to 64. The ID  gets used when generating MAC address and the UUIDS, or unique identifiers for virtual machines. You can see that if two vCenter servers had the same unique ID, a possibility exists that duplicate MAC addresses might get generated; cue packet loss, connectivity issues and your desk phone ringing a lot…

So what do we do?

Solution: If you deploy virtual machines from multiple vCenter Server systems to the same network, you must ensure that these vCenter Server systems have unique instance IDs. How can you check the ID of each vCenter server? It’s simple.. login to vCenter, and go to Administration, vCenter Server Settings. Click Runtime settings and you can see the unique ID.

Simply, do this on each vCenter server. If you have a duplicate ID, change it! Just dont forget to restart the vCenter services afterwards!


VMware Provide SDK/API Support Offering

If you spend any time developing applications and utilities (like these) utilising the VMware APIs then there is a high probability that you will have hit a brick wall at some point during the process. The VMware APIs aren’t the easiest in the world to work with. However, once you get past the first few common hurdles you will find that there is a refreshing amount of functionality and information in there which will keep you up all night as you code your next masterpiece!

For those developing commercial offerings there have been some issues with supportability of the API and SDKs in the past.

However, VMware have now launched a bolt on to your support contracts enabling you to obtain a high level of support to make sure you development efforts are successful.

Here is what VMware has to say about it

VMware is happy to announce that the SDK Support Program is now available for direct order. The offering helps developers get vSphere solutions to market more quickly by providing them with access to VMware expert engineers.

Customers can access information at

If you have questions about the offering, please send us an e-mail.

VMware SDK Support Program FAQs:

Q:  What products will the SDK Support Program support?
A:  The following products will be supported:

Products for Administrators:

VMware vSphere PowerCLI
VMware vSphere Command Line Interface
VMware vSphere Management Assistant

Products for Software Developers:

VMware vSphere Web Services SDK
VMware vSphere SDK for Perl
VMware vSphere Guest SDK
VMware vCloud API (Future)
VMware Virtual Disk Development
VMware vSphere Client Plug-ins
VMware vCenter Orchestrator API (creation of custom workflows)

 More information can be found on here

vExpert 2010

When I woke up on Saturday morning I had the great pleasure of an email from John Troyer in my inbox informing me that I have been awarded VMwares vExpert status in 2010 for contributions and effort to the communityduring 2009. I am honored to be given this award. If you haven’t heard of the vExpert award, this is how VMware describe it on the public vExpert page

The VMware vExpert Award is given to individuals who have significantly contributed to the community of VMware users over the past year. vExperts are book authors, bloggers, VMUG leaders, tool builders, and other IT professionals who share their knowledge and passion with others. These vExperts have gone above and beyond their day jobs to share their technical expertise and communicate the value of VMware and virtualization to their colleagues and community.

You can see the VMware vExpert page here. Congratulations to all of the vExpert 2010 recipients, to those at VMware that put the award together and to those who did not receive an award but provide incredible positive efforts in to the VMware community. Lets hope that everyone keeps it up!

Although my blog may sit quiet for a period of time, it is due to the fact that I am publishing material over at Xtravirt, helping out on the communities or, actually out earning some money for a change! But don’t worry, when things go quiet it doesn’t mean that there is nothing going on! There are a load of new whitepapers (free), applications (free) and utilities (yes, free!) that are in the pipeline for 2010. Watch this space!

VMware re-release Update1 for ESX4.0 – Fixes Update1 ‘Issue’

Following a discovered issue with Update 1 for ESX4.0 which was released on the 23rd November, VMware re-relase Update1a to fix the problems. Potentially a situation could occur when the ESX host could be left in an unstable state with the upgrade failing. The issue is caused by an upgrade to a the glibc file contained in Update 1. The new version of glibc (version 5.3) introduces a change to the locking mechanism. Previously, a bug was reported that affected users running HP Insight Manager agents on their ESX hosts. However, the bug also affected users that run RPM commands during the upgrade process.

The fixed version of Update 1 (dubbed Update 1a) fixes the aforementioned issues. Update 1a can be obtained via Update Manager and the patch download site.

The offical KB is here

Update Release of VMware VDR Available

I don’t know how many of you out there have been using VDR to backup your VMware estate. VDR is a good option for a quick deduplicated backup solution – albeit there have been a few issues. Initially Xtravirt used VDR to backup our production infrastructure as well as development and test virtual machines. However, occasionally we were recieving the well documented 3902 error which would stop the backup jobs from running. A sample of this error is below.

11/23/2009 5:33:11 AM: Normal backup using Xtravirt Daily backup

11/23/2009 5:33:48 AM: Failed to create snapshot for XenCenterServer, error -3902 ( file access error)

11/23/2009 5:33:57 AM: Task incomplete

The issue seemed to be resolved by rebooting the VDR virtual appliance, although this brought with it, its own problems (not counting the annoyance of rebooting it every other day). Well, thank goodness VMware have got their finger out and released an updated version that resolves (to be seen and tested) the issue.

VMware VDR

VMware VDR

The upgrade path is documented here. Basically, uninstall your existing VDR plugin from your machine, import the new OVF appliance and connect it to the backup destination (existing VMDK\CIFS share\RDM).  If you are using VDR or are looking at testing it, ensure you use the updated version. Make sure you review the release notes before getting your hands dirty. Although it does not mention the ‘fix’ that is mentioned on the forums here, other information worthy of note included:


The enhancements have been made for this release of Data Recovery.

  • File Level Restore Functionality is Officially SupportedFile Level Restore (FLR) provides a way to access individual files within restore points for Windows virtual machines. In previous versions of Data Recovery, FLR was provided as an experimental feature. File Level Restore feature is now officially supported.

  • Integrity Check Stability and Performance ImprovedThe integrity check process is faster and more stable. Note that integrity checks are computationally intensive processes and can take significant periods of time. The exact amount of time integrity checks take varies based on of the size of the deduplication store. Even with these enhancements, integrity checks that take several hours are not unexpected.

  • Integrity Checks Provides Improved Progress InformationWhen an integrity check is running, a progress indicator is displayed. This progress indicator has been improved, although it does not provide the optimal level of detail.

Enhanced CIFS Shares Support

Perhaps ‘Enhanced CIFS Shares Support’ is code for ‘now works.’

VMware Name me a beast?

When I saw this I have to admit that I started to ge a bit worried. Its not everyday you get a mark like this next to your name.

VMware mark me as a beast

VMware, do you want to tell me something ?!? Someone give me some points or take some away, quick !!

Xtravirt Release Software Utilities

You may have already seen vAlarm, a free utility to monitor alarms from a vcenter server. After I finished writing that application I thought, what would be useful next? So, I have written and released a free log viewer application for esx called VLogView.

Let me know what you think.