Category: Storage

Storage Bus Speeds 2018
By: Date: April 8, 2018 Categories: Storage Tags: ,

Storage bus speeds with example storage endpoints. Bus Lanes End-Point Theoretical Bandwidth (MB/s) Note SAS-3 1 HBA <-> Single SATA Drive 600 SAS3<->SATA 6Gbit SAS-3 1 HBA <-> Single SAS Drive 1200 SAS3<->SAS3 12Gbit SAS-3 4 HBA <-> SAS/SATA Fanout 4800 4 Lane HBA to Breakout (6 SSD)[2] SAS-3 8 HBA <-> SAS/SATA Fanout 8400…

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Creating compressible data with fio.
By: Date: October 18, 2016 Categories: fio Tags: , , ,

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…

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Specifying Drive letters with fio for Windows.
By: Date: October 5, 2016 Categories: fio Tags: , , ,

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…

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Things to know when using vdbench.
By: Date: September 21, 2015 Categories: vdbench Tags: ,

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…

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SATA on Nutanix. Some experimental data.
By: Date: June 16, 2015 Categories: Storage Hardware and Devices Tags: , , ,

The question of  why  Nutanix uses SATA drive comes up sometimes, especially from customers who have experienced very poor performance using SATA on traditional arrays. I can understand this anxiety.  In my time at NetApp we exclusively used SAS or FC-AL drives in performance test work.  At the time there was a huge difference in performance between…

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Multiple devices/jobs in fio
By: Date: June 17, 2014 Categories: fio Tags: ,

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…

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