Storage Performance Archives

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Storage Performance

Effect of POSIX_FADV_SEQUENTIAL and POSIX_FADV_RANDOM on IO performance.

gary
August 22, 2024

Previously we looked at how the POSIX_FADVISE_DONTNEED hint influences the Linux page cache when doing IO via a filesystem. Here…

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Using fio to read from Linux buffer-cache

gary
August 12, 2024

Sometimes we want to read from the Linux cache rather than the underlying device using fio. There are couple of…

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fio versions < 3.3 may show inflated random write performance

gary
February 15, 2023

TL;DR If your storage system implements inline compression, performance results with small IO size random writes with time_based and runtime…

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Specifying Drive letters with fio for Windows.

gary
December 29, 2022

fio on Windows Download pre-compiled fio binary for Windows Example fio windows file, single drive This will create a 1GB…

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Storage Performance

Hunting for bandwidth on a consumer NVMe drive

gary
December 22, 2022

The Samsung SSD 970 EVO 500GB claims a sequential read bandwidth of 3400 MB/s this is a story of trying…

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Storage Performance

Beware of tiny working-set-sizes when testing storage performance.

gary
July 1, 2022

I was recently asked to investigate why Nutanix storage was not as fast as a competing solution in a PoC…

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Using rwmixread and rate_iops in fio

gary
July 14, 2021

Creating a mixed read/write workload with fio can be a bit confusing. Assume we want to create a fixed rate…

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Understanding fio norandommap and randrepeat parameters

gary
May 6, 2021

The parameters norandommap and randrepeat significantly change the way that repeated random IO workloads will be executed, and also can…

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Storage Performance

Identifying Optane drives in Linux

gary
July 15, 2020

How to identify optane drives in linux OS using lspci.

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diskspd

Microsoft diskspd Part 3. Oddities and FAQ

gary
April 22, 2020

Tips and tricks for using diskspd especially useful for those familar with tools like fio

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diskspd

Microsoft diskspd. Part 2 How to bypass NTFS Cache.

gary
April 7, 2020

How to ensure performance testing with diskspd is stressing the underlying storage devices, not the OS filesystem.

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diskspd

Microsoft diskspd. Part 1 Preparing to test.

gary
March 30, 2020

How to install and setup diskspd before starting your first performance tests and avoiding wrong results due to null byte…

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Storage Performance

How to identify NVME drive types and test throughput

gary
March 17, 2020

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Storage Performance

Why does my SSD not issue 1MB IO’s?

gary
March 13, 2020

First things First Why do we tend to use 1MB IO sizes for throughput benchmarking? To achieve the maximum throughput…

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Storage Performance

How to identify SSD types and measure performance.

gary
March 9, 2020

The real-world achievable SSD performance will vary depending on factors like IO size, queue depth and even CPU clock speed.…

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Storage Performance

Paper: A Nine year study of filesystem and storage benchmarking

gary
May 6, 2019

A 2007 paper, that still has lots to say on the subject of benchmarking storage and filesystems. Primarily aimed at…

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Storage Performance

Storage Bus Speeds 2018

gary
April 8, 2018

Storage bus speeds with example storage endpoints. Bus Lanes End-Point Theoretical Bandwidth (MB/s) Note SAS-3 1 HBA <-> Single SATA…

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Storage Performance

The return of misaligned IO

gary
May 25, 2017

We have started seeing misaligned partitions on Linux guests runnning certain HDFS distributions. How these partitions became mis-aligned is a…

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Storage Performance

High Response time and low throughput in vCenter performance charts.

gary
May 16, 2017

Often we are presented with a vCenter screenshot, and an observation that there are “high latency spikes”. In the example, the response…

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Creating compressible data with fio.

gary
October 18, 2016

Today I used fio to create some compressible data to test on my Nutanix nodes. I ended up using the…