Hi,
The storage quota takes into account virtual size of active VM's disks, actual size of snapshots and actual size of templates. So the active VM disk needs 40GB of quota, but snapshots need only the size they actually consume.
In case the disk is preallocated, the first snapshot will have actual size the same as virtual size. So the VM with snapshot will need quota twice as big.
Currently it is not possible to exclude snapshots from the quota.
As a partial workaround, try setting the allocation policy of the disk to 'Thin Provision'.
There are config values that change the default threshold and grace values, but they are not exposed through the engine-config utility. Currently the only way to change them is to update the DB table 'vdc_options' directly.
The names of the config options are: 'QuotaThresholdCluster', 'QuotaThresholdStorage', 'QuotaGraceCluster', 'QuotaGraceStorage'. The grace values are only what is above 100%, so grace value 20 is 120%.
The table can be updated for example by:
UPDATE vdc_options SET default_value = 20 WHERE option_name = 'QuotaGraceStorage';
The config values are cached, so the ovirt-engine service needs to be restarted after updating the DB.
Best regards,
Andrej