VSAN Part 21 – What is a witness?

At this stage, VSAN has only been in GA for a number of weeks, even though many of us here at VMware have been working on it for a year or two (or even more). Sometimes when we get into explaining the details of storage objects, components, etc, we forget that this is all so new for so many people. In a recent post, someone asked me to explain the concept of a witness on VSAN. Looking back over my posts, I was surprised to realize that I hadn’t already explained it. That is the purpose of this post – explain what a witness disk is in VSAN, and what role it provides.

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VSAN Part 18 – VM Home Namespace and VM Storage Policies

Well, VSAN is finally GA today. Check out Duncan’s blog post which has lots of good links about where to get the GA bits.

In this post, I am going to address a question about the VM Home Namespace object on VSAN which has come up a number of times recently and has caused a little bit of confusion. If you’ve been following my series of Virtual SAN articles, you may recall that virtual machines deployed on a VSAN datastore are now made up as a set of objects (as opposed to the set of files that we’ve been used to traditionally). These objects may be virtual machine disk (VMDKs), snapshot deltas, VM swap space and of course the VM Home Namespace. The VM Home Namespace is where we store all the virtual machine configuration files, such as the .vmx, .log, digest files, memory snapshots, etc. Now what a number of folks have noticed is that even though they set a VM Storage Policy with various VSAN capabilities, the VM Home Namespace object does not seem to implement the policy settings when viewed via the vSphere web client. This post will aim to explain why.

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Storage DRS Default VM Affinity Setting

[Updated] This is a very short post as I only learnt about this recently myself. I thought it was only available in vSphere 5.5 but it appears to be in vSphere 5.1 too. Anyhow Storage DRS now has a new setting that allows you to configure the default VM affinity setting. Historically, VMDKs from the same virtual machine were always kept together on the same datastore by default; you had to set a VMDK anti-affinity rule to keep them apart. Now you can set a default for this option, which can either be to keep VMDKs together on the same datastore or to keep VMDKs apart on different datastores.

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Hot-Extending Large VMDKs in vSphere 5.5

In my recent post about the new large 64TB VMDKs available in vSphere 5.5, I mentioned that one could not hot-extend a VMDK (i.e. grow the VMDK while the VM is powered on) to the new larger size due to some Guest OS partition formats not being able to handle this change on-the-fly. The question was whether hot-extend was possible if the VMDK was already 2TB or more in size. I didn’t know the answer, so I decided to try a few tests on my environment. Continue reading

vSphere 5.5 Storage Enhancements Part 1: 62TB VMDK

Regular readers will know that I’ve spent a lot of time recently posting around VSAN. But VSAN wasn’t the only announcement at VMworld 2013. We also announced the next release of vSphere – version 5.5. I now want to share with you a number of new storage enhancements which we have made in this latest release of vSphere. To begin with, we will look at a long-awaited feature, namely the ability to have virtual machine disk files that are larger than 2TB, the traditional maximum size of VMDKs.

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What happens when VMFS heap depletes completely?

I’ve blogged about the VMFS heap situation numerous times now already. However, a question that I frequently get asked is what actual happens when heap runs out? I thought I’d put together a short article explaining the symptoms one would see when there is no VMFS heap left on an ESXi host. Thanks once again to my good friend and colleague, Paudie O’Riordan, for sharing his support experiences with me on this matter – “together we win”, right Paud?

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Raxco introduces PerfectStorage – Guest OS Space Reclaim

raxco-imageI was first introduced to Raxco Software when I wrote an article on the vSphere Storage Blog related to fragmentation on Guest OS file systems. In that post, I wanted to highlight some side effects of running a defragment operation on the file system in the Guest OS (actually, primarily the Windows defragger). Raxco reached out to say that they had a product that would actually prevent fragmentation occurring in the first place, which was rather neat I thought. Bob Nolan, Raxco’s CEO reached out to me again recently to let me know about a new product that they were launching on the market (on April 23rd, 2013). If you’re looking for a solution to reclaim dead space from within a Guest OS, then read on.

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