John Nicholson

Recent Posts

Licensing Applications on vSAN?

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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?)

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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

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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)

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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)

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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)

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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)

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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...
Steve Jurvetson CC

Why Performance Consistency (and All Flash Virtual SAN) Matters.

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If an application is occasionally timing out, or experiencing inconstant performance shouldn’t we consider it “down or unavailable”?   Years ago I walked into a meeting with a customer and as the CIO walked in he asked his staff what their prime directive was. Not skipping a beat they all in unison stated “To provide a reliable Read more...

VMware Virtual SAN and SAS Expanders

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I’ve received a number of questions from customers about using SAS expanders for external, or internal storage. I would like to clear up any confusion and discuss what is supported (and more importantly why!) SAS expanders are supported only on VSAN ready nodes. Virtual SAN Ready Node is a validated server configuration in a tested, certified Read more...