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Using fio to read from Linux buffer-cache
Sometimes we want to read from the Linux cache rather than the underlying device using fio. There are couple of…
Tag: fio
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fio versions < 3.3 may show inflated random write performance
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.
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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Hunting for bandwidth on a consumer NVMe drive
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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Beware of tiny working-set-sizes when testing storage performance.
I was recently asked to investigate why Nutanix storage was not as fast as a competing solution in a PoC…
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Single threaded DB performance on Nutanix HCI
tl;dr A Nutanix cluster can persist a replicated write across two nodes in around 250 uSec which is critical for…
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Using rwmixread and rate_iops in fio
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
The parameters norandommap and randrepeat significantly change the way that repeated random IO workloads will be executed, and also can…
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How to identify SSD types and measure performance.
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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How to run vertica vioperf tool
The vertica vioperf tool is used to determine whether the storage you are planning on using is fast enough to…
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Working with fio “distribution /pereto” parameter
The fio Pareto parameter allows us to create a workload, which references a very large dataset, but specify a hotspot…
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The return of misaligned IO
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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High Response time and low throughput in vCenter performance charts.
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.
Today I used fio to create some compressible data to test on my Nutanix nodes. I ended up using the…
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Things to know when using vdbench.
Recently I found that vdbench was not giving me the amount of outstanding IO that I had intended to configure…
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Multiple devices/jobs in fio
If your underlying filesystem/devices have different response times (e.g. some devices are cached – or are on SSD) and others…
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Here be Zeroes
Many storage devices/filesystems treat blocks containing nothing but zeros in a special way, often short-circuiting reads from the back-end. This…