To reduce quota requests, quota space is initially allocated to QSDs in very large chunks. How much unused quota space can be hold by a target is controlled by the qunit size. When quota space for a given ID is close to exhaustion on the QMT, the qunit size is reduced and QSDs are notified of the new qunit size value via a glimpse callback. Slaves are then responsible for releasing quota space above the new qunit value. The qunit size isn't shrunk indefinitely and there is a minimal value of 1MB for blocks and 1,000 for inodes. This means that the quota space rebalancing process will stop when this mininum value is reached. As a result, quota exceeded can be returned while many slaves still have 1MB or 1,000 inodes of spare quota space.