Write a 2 pages paper on artical review on computer file mgmt. Running Head: ARTICLE REVIEW Article Review: A Storage Slab Allocator for Disk Storage Management in File System By Junwei Zhang, Jinglia

Write a 2 pages paper on artical review on computer file mgmt. Running Head: ARTICLE REVIEW Article Review: A Storage Slab Allocator for Disk Storage Management in File System By Junwei Zhang, Jingliang Zhang Jiangang Zhang, Xiaoming Han and Lu Xu

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Article Review:

A Storage Slab Allocator for Disk Storage Management in File System

By

Junwei Zhang, Jingliang Zhang Jiangang Zhang, Xiaoming Han and Lu Xu

The authors propose a new disk management system based on the idea of slab concept of memory management and call it the storage slab allocator. The find that under their testing that their system increase speed and efficacy of file management on the system while subsequently reducing CPU usage by 40%. If true this could hold substantial value in the computer storage sector and change the way storage is allocated and reused by the operating system, increasing efficiency as well as capacity at the same time.

The authors perform a quick review of the current block allocation and bit allocation storage methods currently in use. In the block allocation method there are policies in place that determine sequence, locality and so on. When the block of data satisfies the requirement they are allocated the space. The difficulty in this method arises when files are deleted. The original relationships are discarded creating truncations in clusters. The relations need to be completely redone for each new block of data. The authors realize this to be an inefficient use of cpu power and time.

The authors suggest that retaining the file layout instead of loosing it after a deletion is a more efficient way to retain block storage. If the file structure no longer has to be recreated each time a file is deleted then a tremendous amount of processor time will be realized. They propose a Storage Slab Allocator or SSA for an improved method of disk space management. Their novel approach appears to have merit as evidenced by the following file management policy. They propose to add a del_list, which tracks any deleted file original layout and a trunc_list, which likewise record any truncated space layout. These are attached to each block Group (BG) for their SSA. They use the binary strategy in the file layout with 1 identified as used and 0 identified as free. they have termed this the “invalid” bit. Thus the strategy becomes:

The total blocks within the sub file layout whose head block number is free are all free. Otherwise, the next level ‘invalid’ need be checked until the last level. Not all the block number but only the head block of the sub file layout need set to be free when blocks are released. (Zhang, et. al., p. 296)

They continue to illustrate the concept as a linear but progressive approach that retains the valuable file storage structures while being able to relinquish or delete the data more quickly. Then subsequently allowing new data to be allocated as a “slab” of information rather then being parsed out in bit format and recreating a file structure, often along truncated space that has not been adequately allocated for use.

They created a prototype system and test three levels of operations. They compare the fully matched (SSA_match) and not fully matched (SSA_notmat) reused allocation performance of SSA with Ext3 bitmap. Using Allocation Cost as their goal and files size as their main test they produced the following results:

The results are that SSA match allocation had the best performance, outperforming the Ext3 by 100%. However they also noted that SSA notmat allocation improves as the free file layout size increases. However they realize there is more work to be done to make this a viable file system. There often needs to be a way to protect the unused areas from restructuring in order to retrieve data and they propose a time value system to protect areas for a certain amount of time. But their work certain shows great promise for the future of storage media mechanics.

References

Zhang, Junwei, Zhang, Jingliang, Zhang, Jiangang, Han,Xiaoming & Xu, Lu. (2009). A Storage Slab Allocator for Disk Storage Management in File System. IEEE International Conference on Networking, Architecture, and Storage Pp.