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Disk Experiment

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The Disk experiment fills up a target block device (specified by the filesystem on which it is mounted) by writing to files at the destination specified by <span class="code-class-custom">--dir</span>. The number of files written directly corresponds to the number of <span class="code-class-custom">--workers</span> specified.

Considerations for Container Attacks

  • The Disk experiment can target the ephemeral storage (e.g. <code>rootfs</code>) or externally mounted storage attached to your container, such as a directory backed by a Kubernetes PersistentVolumeClaim.
  • If a target of a Disk experiment is killed during while the experiment is running, Gremlin relies on the garbage collection routines of the container platform to remove any impact to the terminated container's ephemeral storage. In most cases this is done automatically by the container platform on an as-needed basis. For Kubernetes users, see Garbage collection of unused containers and images. Impact to external volumes mounted by the target are automatically cleaned up when the target terminates.
  • The Disk expeirment for containers is not supported with the following legacy container drivers: <code>docker-runc</code>, <code>containerd-runc</code>, <code>crio-runc</code>, <code>docker (legacy)</code>. Users should use the latest <code>linux</code> container drivers. See Declare Container Driver.

Options

ParameterFlagRequiredDefaultVersionDescription
Dir-d pathFalse/tmp1.8.0The root directory for the IO experiment.
Workers-w intFalse11.8.0The number of diskwrite workers to run concurrently.
Block Size-b intFalse41.8.0Number of Kilobytes (KB) that are read/written at a time.
Volume Percentage-p <0-100>False1001.8.0Percent of Volume to fill (0100).
Length-l intFalse601.8.0The length of the experiment (seconds).

Note
Azure Windows instances may throttle disk I/O such that large disk experiments will take an excessive amount of time to complete.
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