ephemeral_disk Block

The ephemeral_disk block describes the ephemeral disk requirements of the group. Ephemeral disks can be marked as sticky and support live data migrations. All tasks in this group will share the same ephemeral disk.

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

The ephemeral disk can be referenced under alloc/data/. More information can be found in the filesystem internals.

Each job's logs will be written to ephemeral disk space. See the logs documentation for more information.

ephemeral_disk Parameters

• migrate (bool: false) - When sticky is true, this specifies that the Nomad client should make a best-effort attempt to migrate the data from a remote machine if placement cannot be made on the original node. During data migration, the task will block starting until the data migration has completed. Migration is atomic and any partially migrated data will be removed if an error is encountered. Note that data migration will not take place if a client garbage collects a failed allocation or if the allocation has been intentionally stopped via nomad alloc stop, because the original allocation has already been removed.

• size (int: 300) - Specifies the size of the ephemeral disk in MB. The current Nomad ephemeral storage implementation does not enforce this limit; however, it is used during job placement.

• 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 blocks. Remember that the ephemeral_disk block 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
}