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Microsoft diskspd Part 3. Oddities and FAQ

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

Microsoft diskspd. Part 2 How to bypass NTFS Cache.

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

Microsoft diskspd. Part 1 Preparing to test.

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

Creating compressible data with fio.

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Today I used fio to create some compressible data to test on my Nutanix nodes.  I ended up using the following fio params to get what I wanted.   buffer_compress_percentage=50 refill_buffers buffer_pattern=0xdeadbeef buffer_compress_percentage does what you’d expect and specifies how compressible the data is refill_buffers Is required to make the above compress percentage do what you’d […]

Specifying Drive letters with fio for Windows.

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Simple fio file for using Drive letters on Windows. This will create a file called “fiofile” on the F:\ Drive in Windows.  Notice that the specification is “Driveletter” “Backslash” “Colon” “Filename” In fio terms we are “escaping” the “:” which fio traditionally uses as a file separator. [global] bs=1024k size=1G time_based runtime=30 rw=read direct=1 iodepth=8 […]

Things to know when using vdbench.

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Recently I found that vdbench was not giving me the amount of outstanding IO that I had intended to configure by using the “threads=N” parameter. It turned out that with Linux, most of the filesystems (ext2, ext3 and ext4) do not support concurrent directIO, although they do support directIO. This was a bit of a […]

Multiple devices/jobs in fio

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If your underlying filesystem/devices have different response times (e.g. some devices are cached – or are on SSD) and others are on spinning disk, then the behavior of fio can be quite different depending on how the fio config file is specified.  Typically there are two approaches 1) Have a single “job” that has multiple […]