open-nomad/website/source/docs/job-specification/ephemeral_disk.html.md

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docs	ephemeral_disk Stanza - Job Specification	docs-job-specification-ephemeral_disk	The "ephemeral_disk" stanza instructs Nomad to utilize an ephemeral disk instead of a hard disk requirement, and can also enable sticky volumes and live data migrations.

ephemeral_disk Stanza

Placement	job -> group -> **ephemeral_disk**

The ephemeral_disk stanza instructs Nomad to utilize an ephemeral disk instead of a hard disk requirement. Clients using this stanza should not specify disk requirements in the resources stanza of the task. All tasks in this group will share the same ephemeral disk.

job "docs" {
  group "example" {
    ephemeral_disk {
      migrate = true
      size    = "500"
      sticky  = true
    }
  }
}

ephemeral_disk Parameters

• migrate (bool: false) - Specifies that the Nomad client should make a best-effort attempt to migrate the data from a remote machine if placement should fail. During data migration, the task will block starting until the data migration has completed.

• size (int: 300) - Specifies the size of the ephemeral disk in MB.

• sticky (bool: false) - Specifies that Nomad should make a best-effort attempt to place the updated allocation on the same machine. This will move the local/ and alloc/data directories to the new allocation.

ephemeral_disk Examples

The following examples only show the ephemeral_disk stanzas. Remember that the ephemeral_disk stanza is only valid in the placements listed above.

Sticky Volumes

This example shows enabling sticky volumes with Nomad using ephemeral disks:

ephemeral_disk {
  sticky = true
}