Elastic Quotas
Despite seemingly endless increases in the amount of storage and ever decreasing costs of hardware, managing storage is still expensive. Additionally, users continue to fill increasingly larger disks, worsened by the proliferation of large multimedia files and high-speed broadband networks. Storage requirements are continuing to grow at a rate of 50% a year. Worse, existing hard disk technology is reaching physical limitations, making it harder and costlier to meet growing user demands . Storage management costs have remained a significant component of total storage costs. Even in the '70s, storage costs at IBM were several times more than hardware costs, and projected that they would reach ten times the cost of the hardware. Today, management costs are five to ten times the cost of underlying hardware and are actually increasing as a proportion of cost because administrators have a limited amount of storage each can manage.
Up to 47% of storage costs are associated with administrators manually manipulating files .Thankfully, significant savings are possible: studies show that over 20% of all files--representing over half of the storage-are regenerable . Other studies, indicate that 82%-85% of storage is allocated to files that have not been accessed in more than a month. The studies shows that storage management has been a problem in a past, continues to be a problem today, and is only getting worse--all despite growing disk sizes. Recent trends have begun to address the management of storage through virtualization . Morris put forth the idea of Autonomic Computing, which includes "the system's ability to adjust to its configuration and resource allocation to achieve predetermined goals" .
Elastic Quota system is designed to help the management problem via efficient allocation of storage while allowing users maxi-mal freedom, all with minimal administrator intervention.Elastic quotas enter users into an agreement with the system: users can exceed their quota while space is available, under the condition that the system will be able to automatically re-claim the storage when the need arises. Users or applications may designate some files as elastic.
