How to deploy Ubuntu cloud images to Nutanix AHV

Posted on by gary

In this example we use the KVM cloud image from the Canonical Ubuntu image repository. More information on Ubuntu cloud images is on the canonical cloud image page. More detail on the cloud image boot process and cloud-init here: Ubuntu UEC/Imanges.

We can use the Ubuntu cloud image catalog, and specifically use one that has been built to run on KVM. Since AHV is based on KVM/QEMU Nutanix can use that image format directly without any further conversion.

Using a cloud image can be a quicker way to stand up a particular version of Linux without having to go through the Linux installation process (choosing usernames, keyboard types, timezones etc.). However, you will need to pass in a public key so that you can login to the instance once it has booted.

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Nutanix Performance for Database Workloads

Posted on by gary

We’ve come a long way, baby.

Full disclosure. I have worked for Nutanix in the performance engineering group since 2013. My opinions are likely biased, but that also gives me a decent amount of context when it comes to the performance of Nutanix storage over time. We already have a lot of customers running database workloads on Nutanix. But what about those high-performance databases still running on traditional storage?

I dug out a chart that I presented at .Next in 2017 and added to it the performance of a modern platform (AOS 6.0 and an NVME+SSD platform). For this random read microbenchmark performance has more than doubled. If you took a look at a HCI system even a few years back and decided that performance wasn’t where you needed it – there’s a good chance that the HW+SW systems shipping today could meet your needs.

Much more detail below.

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Using rwmixread and rate_iops in fio

Posted on by gary

Creating a mixed read/write workload with fio can be a bit confusing. Assume we want to create a fixed rate workload of 100 IOPS split 70:30 between reads and writes.

Don’t mix rwmixread and rate_iops
TL;DR

Specify the rate directly with rate_iops=<read-rate>,<write-rate> do not try to use rwmixread with rate_iops. For the example above use.

rate_iops=70,30

Additionally older versions of fio exhibit problems when using rate_poisson with rate_iops . fio version 3.7 that I was using did not exhibit the problem.

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Cross rack network latency in AWS

Posted on by gary

I have VMs running on bare-metal instances. Each bare-metal instance is in a separate rack by design (for fault tolerance). The bandwidth is 25GbE however, the response time between the hosts is so high that I need multiple streams to consume that bandwidth.

Compared to my local on-prem lab I need many more streams to get the observed throughput close to the theoretical bandwidth of 25GbE

# iperf StreamsAWS ThroughputOn-Prem Throughput
14.8 Gbit21.4 Gbit
29 Gbit22 Gbit
418 Gbit22.5
823 Gbit23 Gbit
Difference in throughput for a 25GbE network on-premises Vs AWS cloud (inter-rack)