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V Blog Posts

Collection by Cormac Hogan


A list of favorite VMware and virtualization relatedblog posts

Cormac Hogan
See you at VMworld 2017 Logos, World, Logo, The World

See you at VMworld 2017 - CormacHogan.com

Like I usually do around this time of year, I wanted to share with you my plans for this year’s VMworld in Las Vegas. Hey, you might even like what you read about my sessions enough to sign up for one 🙂 Once again, I am completely HCI (hyper-converged infrastructure) and storage focused. But what is really exciting for me this year is that I have some new people to co-present with. First of all, I’m presenting a vSAN network deep-dive with Andreas Scherr. Andreas manages all of our vSAN…

Hyper-Converged Infrastructure (HCI), Sustainability and Green IT Sustainability, Storage, Purse Storage, Larger, Sustainable Development, Store

Hyper-Converged Infrastructure (HCI), Sustainability and Green IT - CormacHogan.com

I’m sure it will come as no surprise to many readers that virtualization has brought (and continues to bring) huge benefits with regards to data center efficiency. I’m sure you are all aware of how virtualization allows you to do more with your servers; no more single server – single application paradigms. No longer do you have huge amount of compute resources left idle on your servers. By being able to run many operating systems and many applications simultaneously on the same single server…

Changing policies on-the-fly with VVols Policy Change, Diving, Vocabulary, Things To Think About, Presentation, Deep, This Or That Questions, Storage, Posts

Changing policies on-the-fly with VVols - CormacHogan.com

Last week, I was presenting at the VMware User Group (VMUG) event in Poland. My topic was SPBM, Storage Policy Based Management. This is the framework for consuming data services, whether these are provided from vSAN, Virtual Volumes or VAIO (IO Filters). You can get the presentation from here. One of the attendees who had implemented Virtual Volumes (aka VVols) asked a very interesting question about changing policies of a VVol based VM on-the-fly. The question is whether a policy change…

Getting to grips with and Kerberos Active, White Paper, Filter, The Past, Ads, Posts, Blog, Messages, Blogging

Getting to grips with NFSv4.1 and Kerberos - CormacHogan.com

Over the past few weeks, I’ve been looking to update some of our older white papers on core storage topics. One of the outdated papers was on NFS, and a lot had changed in this space since the paper was last updated. Most notably, was the introduction of support for NFS v41 in vSphere 6.0, along with Kerberos based authentication. In vSphere 6.5, we also added Kerberos integrity checking. I decided to have a go at configuring this in my own lab. Before going any further, I need to thank…

2-node vSAN - witness network design considerations Consideration, Remote, Posts, Blog, Design, Messages, Blogging, Pilot

2-node vSAN - witness network design considerations - CormacHogan.com

It seems that 2-node vSAN for ROBO (remote office/branch office) deployments are becoming more and more popular. The fact that one can now connect the 2 vSAN hosts at the remote office directly back-to-back without needing a 10Gb switch has reduced the cost extensively. And with the introduction of a vSAN Enterprise for ROBO license edition with vSAN 6.6.1, you get the full feature set of vSAN on 2-node deployments. This new edition builds on the vSAN Advanced edition, and enables the use of…

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Upcoming speaker session at the Poland/Polska VMUG (Warsaw) - CormacHogan.com

I’m delighted to announce that I have been invited back to present at the next Poland/Polska VMUG, which will take place in Warsaw on Wednesday, October 25th, 2017. I have been asked to deliver the keynote at this VMware User Group meeting, and I will be using the opportunity to present on Storage Policy Based Management (SPBM), and how important it is to have a seamless, policy based approach to managing data. It would seem that I am one of the first speakers of the day, so I will have a…

Supporting Fault Tolerance VMs on vSAN Stretched Cluster Design System, Words, Blog, Blogging, Horse

Supporting Fault Tolerance VMs on vSAN Stretched Cluster - CormacHogan.com

During one of our many discussions at VMworld 2017, I was asked about supporting Fault Tolerance on vSAN Stretched Clusters, more specifically SMP-FT. Now to be clear, we can support SMP-FT on vSAN since version 6.1. The difficulty with supporting SMP-FT on vSAN stretched cluster has always been the possible latency between the data sites, which could be up to as much as 5ms. This is far too high to support SMP-FT on a VM that has data replicating between data sites, and for that reason, we…

How many hosts are needed to implement SFTT in vSAN Stretched Cluster? How Many, Ads, Posts, Blog, Messages, Blogging

How many hosts are needed to implement SFTT in vSAN Stretched Cluster? - CormacHogan.com

Many of you who are well versed in vSAN will realize that we released a Secondary Failures To Tolerate (SFTT) feature with vSAN 6.6. This meant that not only could we tolerate failures across sites, but that we could also add another layer of redundancy to each copy of the data maintained at each of the data sites. Of course the cross site replication (now referred to as PFTT or Primary Failures To Tolerate) is still based on RAID-1 mirroring and this continues to require a third site for…

See you at VMworld 2017 Logos, World, Logo, The World

VMworld 2017 Session on vSAN Top 10 things to know now on YouTube - CormacHogan.com

A quick note to let you know that a recorded version of the VMworld 2017 session “Top 10 things to know about vSAN” is now available on YouTube. I delivered this with my colleague, Duncan Epping and in this recording we talk about a bunch of things that we feel are important to know about vSAN, but which you may not be aware of. Hope you like it.

  Site Hosting, Posts, This Or That Questions, Blog, Messages, Blogging

New vSAN Stretched Cluster Topology now supported - CormacHogan.com

After publishing the vSAN Networking Guide earlier this year, Paudie O’Riordain and I received numerous questions regarding support on having different stretched clusters hosting each other’s witness appliances. These queries arose because we discussed a 2-node (ROBO) topology which allowed this to sort of configuration (i.e. the cross hosting of witnesses) via special request. But in the networking guide, we explicitly stated that this was not supported with vSAN stretched clusters…

See you at VMworld 2017 Logos, World, Logo, The World

See you at VMworld 2017 Barcelona - CormacHogan.com

Now that the US VMworld 2017 event in Las Vegas is over for another year, the focus turns to the VMworld 2017 event in Europe. This year, it once again takes place in Barcelona, Spain. A difference this year is that there is not much of a gap between US and European events, with the Europe event taking place in September this year rather than in October like it usually does. Just like the VMworld Las Vegas event, I am co-presenting on three sessions. In additional to that, in Barcelona, I am…

  Storage Containers, Posts, App, Projects, Blog, Log Projects, Storage Bins, Messages, Blue Prints

Project Hatchway - VMware Persistent Storage for Containers - CormacHogan.com

Earlier yesterday, I had the opportunity to sit in on a VMworld 2017 session delivered by one of my colleagues, Tushar Thole. Tushar presented “Project Hatchway” to the audience, and like the description of this post suggests, this is all about providing VMware persistent storage to containers. In a nutshell, volumes can now be created on VMFS, NFS and on vSAN in the form of VMDKs, and these volumes can now be consumed by containers instantiated within a container host, i.e. a virtual…

See you at VMworld 2017 Logos, World, Logo, The World

VMworld 2017 Session on vSphere 6.5 Core Storage now on YouTube - CormacHogan.com

A quick note to let you know that the session that I delivered on day 1 of VMworld 2017 is now available on YouTube. The session is entitled “A Deep Dive into vSphere 6.5 Core Storage Features and Functionality” and I delivered this with Cody Hosterman of Pure Storage. Judging by the feedback, and the number of passing comments I received in the hallways at VMworld over the past 2 days, it seems that this session was very well received indeed. Hope you like it.

See you at VMworld 2017 Logos, World, Logo, The World

PKS Announcement at VMworld 2017 - Pivotal Container Service - CormacHogan.com

VMworld always has lots of new announcements about various VMware products and initiatives. VMworld 2017 is no different. This morning we had the announcement of PKS, the Pivotal Container Service. Yes, that is a K instead of a C in the acronym – this is to highlight the fact that this container service is using Kubernetes. Using a feature called BOSH from Pivotal, customers can provision Kubernetes onto their on-premises vSphere deployments (including VCF – VMware Cloud Foundation). This…

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ATS Miscompare revisited in vSphere 6.5 - CormacHogan.com

Does anyone remember the ATS Miscompare issue? This blog post from 2 years ago might jog your memory. It is basically an issue that arose when we began using ATS, the VAAI Atomic Test and Set primitive, for maintaining the ‘liveness’ of a heartbeat in vSphere 5.5U2. After making this change, a number of customers started to see “ATS Miscompare detected between test and set HB images” messages after upgrading to vSphere 5.5U2 or later. The HB reference in the message is shorthand for…

  Filing System, Pointers, Posts, Blog, Stylus, Messages, Blogging, Workbox System

Improved block allocation mechanism on VMFS-6 - CormacHogan.com

Along with other improvements to VMFS-6, there is also a new block allocation mechanism which aims to reduce lock contention between hosts sharing the same VMFS-6 filesystem. To understand how lock contention could arise, it is important to understand that resources on VMFS are grouped into resource clusters; this is the same for VMFS-6 and earlier versions on VMFS. Resources could be file descriptors, sub-block, file block, pointer blocks, and so on. Historically, we have always tried to…