Optimize Your VM Storage through a No-Charge VMware vSan Assessment

September 17, 2015
Editorial Staff


Editorial Staff

Do you know your current vSphere storage environment performance or capacity constraints? How about the estimated CAPEX & OPEX of your VM storage? Do you need to determine which of your VMs are suitable candidates for Virtual SAN (vSAN)?

The vSAN Assessment is a free SaaS tool that identifies applications, workloads, or VMs from the current vSphere environment, and analyzes the data for optimization opportunities. The vSAN Assessment tool is composed of two components, which together aggregate and present the data as an intuitive one-stop-shop :

  1. Virtual SAN Assessment Tool Collector – The tool (OVF file) deployed into the IT infrastructure that does all the leg work and sends all the collected data to the vSAN Portal.
  2. Virtual SAN Assessment Tool Portal – A public web application that receives the data from the virtual appliance – can be exported into a multiple document types for analysis, such as Excel, PowerPoint, etc.

As VMware’s 2015 Solution Provider Partner of the Year, SoftwareONE is fully capable of answering any and all questions you have related to your VM technology. Pulled from the VMware blog, below are some common questions on vSAN.

How does VSAN protect my data?

Like any enterprise storage product, that can be a long answer, but at a high level:

  • Administrators declare the level of protection they want for their VM’s data via policy, which is applied at provisioning time.  This is expressed in terms of “failures to tolerate”: 0, 1, 2, etc.  Most of the time, people choose FTT=1 which is the default — e.g. basic redundancy.However, a single VSAN cluster can support different policies (and thus different FTT levels) in the same data store — no need to pre-configure storage.  Also, policies can be changed at any time, and VSAN will automatically reconfigure.
  • VSAN differentiates between failed components and removed components, known as DEGRADED and ABSENT internally.  The idea is that an admin might be rebooting a server, changing a network, or moving around stuff — and the component is missing only temporarily and is expected to return shortly — so no need to do a full reprotect.
  • If VSAN detects a hard device failure (e.g. a failed disk drive or controller), it declares DEGRADED and immediately begins reprotecting data using other resources in the cluster.  If instead VSAN detects that a good component has simply gone missing (e.g. ABSENT) it waits 60 minutes before deciding it’s gone for good and starts reprotecting.  This value is configurable.
  • Protection against network partitions is done through a quorum voting algorithm.  If the network partitions for some reason, >50% of the votes for a given storage object is needed to allow reads and writes to proceed.  This protects against split-brain syndrome.

There’s much more detail available, of course, but these are the core concepts.

My storage team has concerns about VSAN — what should I say?

The goal of VSAN was to make storage essentially “disappear” from the perspective of the vSphere administrator: very simple, no special skills required.

The industry has been using the external storage array model for over twenty years, and — by comparison — VSAN doesn’t look like an external storage array, so there’s that.  And storage people can be very conservative by nature.

On the other hand, vSphere admins are pretty adamant about the need for change.  They point out it’s wasteful and inefficient to have to go to the storage team for each and every thing they need.  Why not let the vSphere admin do storage?

The debate ends up being around two things:

  • Are the benefits worth introducing a new technology?  Even a simple VSAN TCO analysis will open a lot of eyes — both capex and opex.
  • Where does it best fit?  — identifying the parts of the environment where it makes sense to continue with a traditional external storage model, and parts of the environment where it makes sense to collapse storage into the hypervisor with VSAN.

The real win for the storage team is that they now have more time to go work on things that require their specialized expertise vs. day-to-day routine operations.

How fast can VSAN go? How big can it get? Does it show linear scalability?

VSAN is software — scale and performance is mostly a function of the hardware you bring: CPU, memory, network, flash, controllers, etc.  Every time the hardware gets faster, VSAN gets faster as a result — and there’s plenty of cool new hardware always coming to market.

As far as maximum size, the math is easy: up to 64 servers in a cluster, and each server supports up to 35 capacity devices (five disk groups, seven capacity devices each).  A bit of quick math yields a max of 2240 capacity devices.  Using 4TB drives, that’s just shy of 9PB raw in a single cluster.  Probably more than you need.

We’ve published multiple tests that show linear scalability as you add more nodes.  Performance also scales as you put more devices into each server: disk groups, flash cache and capacity devices — scale up as well as scale out.

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