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[Augustina Ragwitz <1509304@xxxxxxxxxxxxxxxxxx>]

Marked as invalid, this is a feature request.

** Changed in: nova
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/1509304

Title:
  Add support for 'l2-cache-size' (a QCOW2 run time option for metadata
  cache size) for drives

Status in OpenStack Compute (nova):
  Invalid

Bug description:
  QCOW2 performance can be significantly improved by setting the l2
  -cache-size parameter for large qcow2 based storage (such as images
  and ephemeral drives) (see
  https://events.linuxfoundation.org/sites/events/files/slides/p0.pp_.pdf).

  Adding support for this optional parameter (which adds [...]-drive
  file=hd.qcow2,l2-cache-size=2097152 to the qemu CLI) would allow
  operators and/or users to configure a more tuned configuration.

  A simple implementation where a default value could be set in
  nova.conf would already give an improved flexibility. A formula could
  also be used with a factor relative to the size of the storage.

  Ideally, this could also be specified as an image or flavor property
  so that only large drives would need to allocate the additional
  memory.

  I could not locate an option such as this in the OpenStack versions up
  to Liberty.

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