Question on Data location - SSD or Spinning disk on a host

  • 16 September 2016
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I have a question that might be as a result of old way of thinking/old storage arrays and might be overthinking this :(

In Nutanix, VM data is local on a host. For a particular VM, some of it's data/blocks may reside on SSD or Magnetic/spinning disk depending on how hot or cold the data is. I have two questions around this.

  1. Is there a way to tell from the Prism dashboard or via cli, for a particular host, where it's data/blocks reside? Put another away,Is there a way to tell %wise for a particular VM how much of it's blocks are on SSD vs spinning/magnetic disk?
  2. If i was conducting a migration from an old/traditional setup to a nutanix cluster, how does the Nutanix node know how much of the VM's blocks to place on SSD vs on spinning?
Thanks all for your time,
Sky.

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RE Q1: In Prism you can tell on a container level, not a VM level (yet, working on that). There's a way to dig in via CLI, but its pretty deep in the weeds.

RE Q2: Nutanix measures access patterns and demands, so of course as the old VM is coming in from the old infrastructure, it doesn't know what was previously hot or not, but the cool thing about nutanix is that it is realtime, so as the VM starts doing its thing on new setup, it will start machine learning about what the workload looks like, and start setting up the tiering.

Also, the obvious answer to all of this at a higher level is, if there is any concern that latency-sensitive data is going ever be on a spinning disk, just eliminate spinning disks and go all-flash. 🙂 Pricing on flash has come way down in the past few years, and the economics of $/GB is helped greatly by the data reduction and avoidance technologies we have built into the system, like compression, dedupe, and so on

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