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
7c7a25aa1e is not in stable/train
nova/virt/libvirt/driver.py due to
I52fbbcac9dc386f24ee81b3321dd0d8355e01976 is not in stable/train
Changes in imagechache.py, workarounds.py and test_imagecache.py are
due to I3c49825ac0d70152b6c8ee4c8ca01546265f4b80 not in stable/train
Change-Id: If874f018ea996587e178219569c2903c2ee923cf
Closes-Bug: #1878024
(cherry picked from commit 89fe504abf)
(cherry picked from commit 968981b585)
90c70f04d7