If the nova compute image cache is on the same disk as the instance
directory then the images in the cache will consume the same disk
resource as the nova instances which can lead to disk overallocation.
This patch adds a new config option
[workarounds]/reserve_disk_resource_for_image_cache . If it is set the
libvirt driver will reserve DISK_GB resources in placement for the
actual size of the image cache.
This is a low complexity solution with known limitations:
* Reservation is updated long after the image is downloaded
* This code allows the reservation to push the provider into negative
available resource if the reservation + allocations exceed the total
inventory.
Conflicts:
nova/conf/workarounds.py due to
Ie38aa625dff543b5980fd437ad2febeba3b50079 ("Add support for translating CPU
policy extra specs, image meta") is not in stable/stein
nova/tests/unit/virt/libvirt/test_driver.py due to
I25d70aa09080b22d1bfa0aa097f0a114de8bf15a ("Add reshaper for PCPU")
is not in stable/stein
Change-Id: If874f018ea996587e178219569c2903c2ee923cf
Closes-Bug: #1878024
(cherry picked from commit 89fe504abf)
(cherry picked from commit 968981b585)
(cherry picked from commit 90c70f04d7)
86be251451