John Nicholson, Author at Virtual Blocks

Designing vSAN Networks – Why Should I Use the Distributed Switch?

John Nicholson posted January 19, 2017

The vSphere Distributed Switch (VDS) is a powerful, but often misunderstood technology that is included with VMware vSAN. This post will review some of my favorite settings on the VDS, and how you can use them to get better control, performance, and visibility into your virtual SAN cluster. While it is most known for the ability Read more...

Designing vSAN Networks – Using Multiple Interfaces?

John Nicholson posted January 18, 2017

vSAN can leverage a number of core ESXi networking features to increase performance and availability. vSAN VMkernel ports should always be configured to use more than one interface to preserve availability in the event of a link failure. There are a number of ways to configure this fail over. Which will you choose? While there Read more...

Designing vSAN Disk groups – All Flash Cache Ratio Update

John Nicholson posted January 18, 2017

vSAN cache recommendations for vSAN 5.5 were 10% of used capacity. With the addition of all all flash in 6.0 it stayed at 10% and Cormac here explains the math behind this. Now if you look closely you’ll notice a few issues as vSAN and flash drives have progressed. The 10% ratio guidelines was based on a Read more...

Licensing Applications on vSAN?

John Nicholson posted January 4, 2017

I wanted to highlight that a lot of questions come up asking about how to control licensing Oracle and other business critical applications on vSAN. Thankfully there are tools in vSphere to enforce and monitor licensing complaince on vSAN clusters. There is no need for storage only nodes, isolated vCenters, isolated clusters, to keep licensing costs Read more...

vSAN stripes (How, When and Why?)

John Nicholson posted September 19, 2016

Number of Disk Stripes Per Object/Stripe Width Number Of Disk Stripes Per Object, commonly referred to as stripe width, is the setting that defines the minimum number of capacity devices across which each replica of a storage object is distributed. vSAN may actually create more stripes than the number specified in the policy for reasons Read more...

Virtual SAN Performance Service and Performance Tools

John Nicholson posted July 12, 2016

One of the exciting new features of Virtual SAN 6.2 is the new performance service. For quick troubleshooting of issues, or verification of performance it is a great and simple tool that can be turned on with a single checkbox. This is an ESXi native performance monitoring system with API, as well as UI access. For Read more...

The Data Locality Discussion (Revisited Part 2)

John Nicholson posted June 28, 2016

This is part 2 of this post. Part one can be found here. As we discussed in the previous blog post, and white papers networking latency is significantly lower than typical flash device latency, however there are some new exception cases that have come up as the Virtual SAN platform has been extended. Client Cache Read more...

The Data Locality Discussion (revisited Part 1)

John Nicholson posted June 9, 2016

Back in 2014, Rawlinson Rivera made the case explaining how Virtual SAN took advantage of data locality with both temporal and spacial locality. He explains how intelligent prefetch algorithms save disk, and reduce latency. The Virtual SAN caching white paper goes into more detail on this. A key point in this paper was that Virtual SAN did Read more...

Scale up VMware Virtual SAN to scale down risk (Part 2)

John Nicholson posted June 4, 2016

This is part 2 of the series. Click here for the first part. FTT=2 With Three Hosts Failing Now for our next example we wanted to look at what would happen if 3 hosts were lost simultaneously while using FTT=2 what would the impact be. As FTT=2 two policies require larger clusters by default (6 hosts Read more...

Scale up VMware Virtual SAN to scale down risk (Part 1)

John Nicholson posted May 30, 2016

I was recently helping a customer design a highly resilient Virtual SAN deployment for tier 1 applications. One thing that was clear was that the traditional rules for designing traditional Tier 1 modular storage arrays were not always applicable. Rule of scaling storage risk: consolidating more workloads to a storage system increases efficiency, but also Read more...

John Nicholson

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