try to use slider for disksize

app/UI/Disk/Forms/CreateForm.php

@@ -55,7 +55,7 @@ class CreateForm extends BaseForm implements ClientArea
         $resourceManager = new ResourceManager();
         $field = new Range('size', 5, $resourceManager->disk()->free());
         $field->addValidator(new NumberValidator($resourceManager->disk()->getMin(),$resourceManager->disk()->free(), true));
-        $field->setDefaultValue($this->configuration()->serverDiskSize->min);
+        $field->setDefaultValue(5);
         $this->addField($field);
         //bus
         if(count($this->configuration()->getAdditionalDiskType()) > 1){