Hello,
I have a small export domain while doing a test.
So I would like to temporarily lower down warning and critical to the minimum, so that I complete the test and then I re-enable default ones:
Initial situation with "engine-config -g"

CriticalSpaceActionBlocker: 5 version: general
WarningLowSpaceIndicator: 10 version: general

This is confirmed by what I see in RACTOREXP export storage domain general pane:

Size: 49 GB
Available: 38 GB
Used: 11 GB

Warning Low Space Indicator: 10% (4 GB)
Critical Space Action Blocker: 5 GB

I set both to 1
[root@ovmgr1 ~]# engine-config -s WarningLowSpaceIndicator=5
[root@ovmgr1 ~]# engine-config -s CriticalSpaceActionBlocker=1

Systemctl restart ovirt-engine

[root@ovmgr1 ~]# engine-config -a|grep "Space[A,I]"
CriticalSpaceActionBlocker: 1 version: general
WarningLowSpaceIndicator: 1 version: general
[root@ovmgr1 ~]#

But the storage domain still shows the previous values in webadmin gui.
I tried also to put in maintenance the storage domain and then activate it again but no change.
And if I try to export a VM with 30Gb of disk I get the error and in the engine log

2017-02-12 20:44:44,872+01 INFO   [org.ovirt.engine.core.vdsbroker.irsbroker.GetVmsInfoVDSCommand] (default task-1
2) [97705aa9-f082-4e79-9e6b-b5bf0dde3666] START, GetVmsInfoVDSCommand( GetVmsInfoVDSCommandParameters:{runAsync='
true', storagePoolId='588237b8-0031-02f6-035d-000000000136', ignoreFailoverLimit='false', storageDomainId='8846db3f-6e07-4468-bbfc-bf5fbc3f8eef', vmIdList='null'}), log id: 2b56a855
2017-02-12 20:44:45,882+01 INFO  [org.ovirt.engine.core.vdsbroker.irsbroker.GetVmsInfoVDSCommand] (default task-1
2) [97705aa9-f082-4e79-9e6b-b5bf0dde3666] FINISH, GetVmsInfoVDSCommand, log id: 2b56a855
2017-02-12 20:44:47,324+01 INFO  [org.ovirt.engine.core.bll.exportimport.ExportVmCommand] (default task-14) [dd88227e-7224-4e02-b2b9-11cb3e6d9ce4] Lock Acquired to object 'EngineLock:{exclusiveLocks='[7c9c686f-6cc6-4db7-8bdd-ee11b82a5266=<VM, ACTION_TYPE_FAILED_OBJECT_LOCKED>]', sharedLocks='null'}'
2017-02-12 20:44:47,382+01 WARN  [org.ovirt.engine.core.bll.exportimport.ExportVmCommand] (default task-14) [dd88227e-7224-4e02-b2b9-11cb3e6d9ce4] Validation of action 'ExportVm' failed for user admin@internal-authz. Reasons:
VAR__ACTION__EXPORT,VAR__TYPE__VM,ACTION_TYPE_FAILED_DISK_SPACE_LOW_ON_STORAGE_DOMAIN,$storageName RACTOREXP
2017-02-12 20:44:47,383+01 INFO  [org.ovirt.engine.core.bll.exportimport.ExportVmCommand] (default task-14) [dd88227e-7224-4e02-b2b9-11cb3e6d9ce4] Lock freed to object 'EngineLock:{exclusiveLocks='[7c9c686f-6cc6-4db7-8bdd-ee11b82a5266=<VM, ACTION_TYPE_FAILED_OBJECT_LOCKED>]', sharedLocks='null'}'
2017-02-12 20:44:47,394+01 ERROR [org.ovirt.engine.api.restapi.resource.AbstractBackendResource] (default task-14
) [] Operation Failed: [Cannot export VM. Low disk space on Storage Domain RACTOREXP.]

What I'm doing wrong?
Thanks,
Gianluca