Author Archive

Heads Up Alert: vSphere 5.5 U1 NFS Random Disconnection Bug!

Just wanted to give my readers a heads up that there appears to be a bug with vSphere 5.5 U1 that impacts any NFS connected storage and can cause random disconnects. The timing of this is a coincidence that it comes right on the coat tails of my previous article Hardware Fails, Software Has Bugs and People Make Mistakes – Usually You Get All At Once! During the disconnects VM’s will appear frozen and the NFS datastores may be greyed out. This appears to impact all vendors and all environments on 5.5. U1 accessing NFS. UPDATED: There is a public KB on this problem from VMware: KB 2076392 - Frequent NFS APDs after upgrading ESXi to 5.5 U1, and VMware is working on it. According to the KB you may experience blue screens of death in Windows, and read only file systems in Linux. I’ve also experienced kernel panics and reboots in Linux as a result of this bug.

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Hardware Fails, Software Has Bugs, People Make Mistakes – Usually You Get All At Once!

Today we experienced the second outage to this blog in the last 12 months. The outage today was 15 hours in total, unacceptably long in my view for a professional hosting company. Very inconvenient to me as I’m sure it was to all of you as well. But this does serve as a good reminder about the maxims of cloud computing.  Mind you the maxims don’t just apply to cloud computing, they are general system design principles that need to be considered and dealt with. But particularly so in Cloud Computing, Outsourcing or Hosting when you are delegating some form of control over your systems to a third party. Maxims are generally established propositions or principles, at least if you’re talking about legal maxims, which I find fascinating to read. But in the context of Cloud Computing the title of this article gives them away. Hardware Fails, Software Has Bugs and People Make Mistakes. It’s up to us to deal with these, as they are guaranteed to happen. This article covers some lessons that can be learned form this recent experience in the hope that we can all have higher availability.

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VCDX Candidate Tips from Down Under Part 1

I read a couple of good articles recently from VCDX candidates that defended at Frimley in the UK. One successful, and one not successful on this occasion. Both articles Extra VCDX Experience Achievement Unlocked by Gregg Robertson and VCDX Recipe for Success by Rene Van Den Bedem (VCDX-133) offer valuable insights. I thought it was worthwhile repeating the comment I made on one of the articles here and I’ll also repeat it in the VCDX community. I don’t know if there will be a part 2 or part n in the future, I’m just planning ahead in case. I hope this offers some help to aspiring VCDX candidates, as well as my other articles on topics relevant to VCDX.

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Using DB Replay to Test Performance and Scalability of Oracle Databases

There are a number of tools available that can assist with testing performance and scalability of Oracle Databases and their platforms including Swingbench, HammerDB, Benchmark Factory for Databases, Apache JMeter, HP Load Runner (with SiteScope) and others. These all do a pretty good job and I’ve used them all at different times for different reasons. But if you want to record and replay a real production Oracle database and test it’s scalability and performance on against a test environment there is another way that’s worth considering.

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#TopvBlog2014 Results Prove VMware has a Fantastic Community

Today Eric Siebert released the results of the Top vBlog results for 2014 with the help of Rick Vanover from Veeam, John Troyer from VMware and David Davis from Pluralsight. Big thanks to Veeam for putting up some awesome prizes this year for bloggers and voters alike. The sheer number of votes and the number of blogs shows what a strong community that VMware has built around its technologies. Eric does a great job every year of running the voting and tallying the results. I think the biggest winners from this are you, our readers, members of the community, technology customers and technology partners. VMware has built a complete community and ecosystem around all the related technologies. I’m very glad that I can be a part of it and share with the community that has been so helpful to me over the years. I greatly appreciate the feedback that I get from you and appreciate your support, which has meant this year I was voted at number 13 spot of the top 25 vBlogs (up 8 places from last year). Congratulations to everyone who made the list this year and especially those that made the top 25 and top 10, your contributions to the VMware community are greatly appreciated. Want to know more, keep reading.

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SQL and Oracle On Nutanix Papers Hot Of The Press

Two papers that have been the result of some of the work I and the team have been doing over the past couple of months at Nutanix have just been published. The first paper is the SQL Server on Nutanix Tech Note that includes a brief outline of why Nutanix is a great place to run SQL Server, as well as the SQL on Nutanix high level best practices and some performance validation results. This is really a shortened overview of the full SQL on Nutanix Best Practices Paper authored by Steven Poitras. The second paper is the Oracle on Nutanix Solution Brief. This paper is really a quick and brief high level overview of the value Nutanix can bring to customers wanting to run Oracle Databases. I would recommend you get these papers as they are hot off the presses. We will be brining you more content specifically around Oracle Database Best Practices in the very near future, including Oracle RAC, and we have a number of vSphere on Nutanix best practices papers in the works.

While I mention the topic of SQL, the book that I’m writing with Michael Corey and Jeff Szastak – Virtualizing SQL Server with VMware: Doing It Right on behalf of VMware Press is also getting close to the finishing line. This contains what you need to know to successfully virtualize SQL Server, even large scale Monster VM instances. The book is due to be published in August in time for VMworld USA, but you can pre-order it now.

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@VMware Completes Software Defined Enterprise and Shakes Up Software Defined Storage

The last week has been big in the world of Software-Defined Storage. VMware has launched the final pillar of the Software Defined Enterprise, Virtual SAN, and just the day after Nutanix announced that it had been granted the patent for its ground breaking software defined storage technology. The VMware launch completes its vision of the Software-Defined Datacenter and Enterprise with all of the major pillars in place, and at the same time intends to shake up the existing SDS market. I have a lot of friends working at VMware and I congratulate them on this major milestone. This launch will broaden the options for customers and keep the other companies in the SDS and hyper-converged field, including the industry leader (where I work) Nutanix,  in check. We will all have to innovate and differentiate in different ways, and try to keep ahead and stay focused. Fortunately there is plenty of market out there for us all and the market is still growing. More than anything though this major launch again validates the entire hyper-converged, scale out software-defined storage mixed with compute architecture and the market as a whole. So how do I think this is going to play with the VMware partnership and other storage vendors, including the likes of Nutanix?

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Using Nutanix Container Reservations and a FreeSpace Container for Availability and Capacity Planning

Over the past week I was discussing vSphere 5.5 best practices with regards to Nutanix with Josh Odgers (Fellow VCDX and member of the Nutanix Solutions and Performance Engineering Team), who is putting together a comprehensive paper on vSphere 5.5 best practices for Nutanix. One of the topics that came up in our discussions was availability and capacity planning, such as the number of node failures to tolerate, and how to make capacity planning easy and ensure you can always meet your failure tolerance. Unlike many storage architectures there is no fixed limit to the number of node failures a Nutanix environment can sustain before data protection may become an issue. It all comes down to your design and how much free space there is to re-protect your data. If for example you have a 64 node Nutanix cluster that is 80% full, you can potentially survive the loss of a more than 10 nodes (from a storage perspective) before your ability to re-product the data becomes an issue. But even at small scale, say 3 nodes, what is the best way to avoid trouble and be able to plan for capacity and failure, and ensure your data is protected?

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Choosing the Right ASM Allocation Unit for a Virtualized Oracle Database

Oracle ASM (Automatic Storage Management) is a volume manager and file system provided by Oracle for use with Single Instance and Real Application Cluster (RAC) databases. Although it supports single instance databases I’ve seen it more commonly used with RAC. ASM provides a high performance and simplified way of managing disks and placing data files and other files for DBA’s. It probably comes as no surprise that Oracle recommends ASM over other options such as OS included or third party volume managers, file systems and raw devices. The ASM Allocation Unit is a fundamental unit of storage and management in any ASM disk group. But which Allocation Unit size should you choose for your Virtualized Oracle Databases?

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Vote For The Best Virtualization Blogs at

Once every year Eric Siebert puts the list together of all of  great virtualization blogs that are written and updated constantly in support of the great community around VMware and virtualization that has been adopted. This is the annual event that gives you an opportunity to show your support and appreciation for all the hours that the bloggers put in, and for you to vote for your favourite and the best virtualization blogs in the world. The list grows ever longer every year, and the number of voters grows ever longer every year also. I love brining you information and advice on virtualizing business critical apps, monster vm’s and everything else vSphere. This is one way I can give back to the community that has been so good to me. If you appreciate what I and the other bloggers do, then please vote for our blogs on the official article at