I was looking at the layout of RAID-5 object configuration the other day, and while these objects were deployed on vSAN with 4 components, something caught my eye. It wasn’t the fact that there were 4 components, which is what one would expect since we implement RAID-5 as a 3+1, i.e. 3 data segments and 1 parity segment. No, what caught my eye was that one of the components had a different vote count. Now, RAID-5 and RAID-6 erasure coding configurations are not the same as RAID-1. With RAID-1, we deploy multiple copies of the data depending on how many…
Sorry about the wordy title but this is a question that has come up a number of times. The request is that when I have two data sites and deploy two stretched clusters across these data sites, can the other stretched cluster support the witness appliance for this stretched cluster, and vice-versa? The answer is no, and I will explain why in this post.
vSAN 6.6 is finally here. This sixth iteration of vSAN is the quite a significant release for many reasons, as you will read about shortly. In my opinion, this may be the vSAN release with the most amount of new features. Let’s cut straight to the chase and highlight all the features of this next version of vSAN. There is a lot to tell you about. Now might be a good time to grab yourself a cup of coffee.
I recently noticed a blog post describing some very strange behaviors in 2-node and 3-node vSAN clusters. I was especially concerned to read that when they introduced a failure and then fixed that failure, they did not experience any auto-recovery. I have reached out to the authors of the post, just to check out some things such as version of vSAN, type of failure, etc. Unfortunately I haven’t had a response as yet, but I did feel compelled to put the record straight. In the following post, I am going to introduce a variety of operations and failures in my…
I’ve recently been involved in some design and sizing for very large VMDKs on vSAN. There are a couple of things to keep in mind when doing this, not just the overhead when deciding to go with RAID1, RAID5 or RAID6, but also what this means for component counts. In the following post, I have done a few tests with some rather large RAID-5 and RAID-6 VMDKs, just to show you how we deal with it in vSAN. If you are involved in designing and sizing vSANs for large virtual machines, you might find this interesting.
VMware has just announced the release of vSphere 6.5 p01 (Patch ESXi-6.5.0-20170304001-standard). While there are a number of different issues addressed in the patch, there is one in particular that I wanted to bring to your attention. Automated UNMAP is a feature that we introduced in vSphere 6.5. This patch contains a fix for some odd behaviour seen with the new Automated UNMAP feature. The issue has only been observed with certain Guest OS, certain filesystems, and a certain block sizes format. KB article 2148987 for the patch describes it as follows: Tools in guest operating system might send unmap…
There has been a lot of discussion in the past around supported topologies for 2-node vSAN, specifically around where we can host the witness. Now my good pal Duncan has already highlighted some of this in his blog post here, but the questions continue to come up about where I can, and where I cannot place the witness for a 2-node vSAN deployment. I also want to highlight that many of these configuration considerations are covered by our official documentation. For example, there is the very comprehensive VMware Virtual SAN 6.2 for Remote Office and Branch Office Deployment Reference Architecture…