42 lines
1.2 KiB
Markdown
42 lines
1.2 KiB
Markdown
# Specifying the I/O properties of a system
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The I/O properties of a system can be specified as a YAML string, by
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using the option --io-properties, or as a YAML file with the option
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--io-properties-file.
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The expected format starts with a map of sections at the top level.
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Currently only `disks` is supported.
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## The disks section
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Inside the `disks` section, the user can specify a list of mount points.
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For each mount point, 4 properties have to be specified (none are
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optional):
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* `read_iops`: read IOPS speed of the device
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* `read_bandwidth`: read bandwidth speed of the device
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* `write_iops`: write IOPS speed of the device
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* `write_bandwidth`: write bandwidth speed of the device
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Additionally the following optional properties can be added:
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* `read_saturation_length`: read buffer length to saturate the device throughput
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* `write_saturation_length`: write buffer length to saturate the device throughput
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Those quantities can be specified in raw form, or followed with a
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suffix (k, M, G, or T).
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Example:
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```
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disks:
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- mountpoint: /var/lib/some_seastar_app
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read_iops: 95000
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read_bandwidth: 545M
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write_iops: 85000
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write_bandwidth: 510M
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write_saturation_length: 64k
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```
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