From f6312699b1b1d876f7c92ccce17bdfdac422f9a4 Mon Sep 17 00:00:00 2001 From: Daniel Wilson Date: Tue, 11 Aug 2015 06:55:49 -0700 Subject: [PATCH] Update backend capabilities on discard/trim/unmap Updating the spec to reflect the fact that hw_disk_discard is not needed and to add detail on how to fully enable this functionality. Implements: bp cinder-backend-report-discard Change-Id: Ibd8fa43bb67b8160c8ba36e817bd83e28f82ec22 --- .../liberty/cinder-backend-report-discard.rst | 24 ++++++++++++++----- 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/specs/liberty/cinder-backend-report-discard.rst b/specs/liberty/cinder-backend-report-discard.rst index 59ae483f..464da108 100644 --- a/specs/liberty/cinder-backend-report-discard.rst +++ b/specs/liberty/cinder-backend-report-discard.rst @@ -20,7 +20,6 @@ instruct Nova how to attach a volume. This spec aims to add the assist to support enabling discard for cinder volumes. - Problem description =================== @@ -101,11 +100,23 @@ See https://en.wikipedia.org/wiki/Trim_(computing) for more info. Other deployer impact --------------------- -Deployers will also have to add a setting to nova.conf to make this work as -well. +Deployers will need to add some properties to Glance images to make +this work. Once an instance is booted from the modified image the +discard capability reported by the driver will be activated. -[libvirt] -hw_disk_discard = unmap +hw_scsi_model=virtio-scsi +hw_disk_bus=scsi + +glance image-update --property hw_scsi_model=virtio-scsi + --property hw_disk_bus=scsi + +This causes the correct controller to be created on the instance +via code changes here https://review.openstack.org/#/c/70263/. +Once the correct controller is in place the unmap functionality +specified by the Cinder backend will be utilized. + +A secondary volume attachment will be treated separately and will +honor the discard settings provided at connection time. Developer impact ---------------- @@ -141,7 +152,8 @@ None Testing ======= -Tempest tests will not be needed for this spec. +Tempest tests will not be needed for this spec. Pure Storage CI will test +this code path with existing tempest tests. Documentation Impact