NDLI: TRAP-Array: A Disk Array Architecture Providing Timely Recovery to Any Point-in-time

Content Provider	IEEE Xplore Digital Library
Author	Qing Yang Weijun Xiao Jin Ren
Copyright Year	2006
Description	Author affiliation: Dept. of Electr. & Comput. Eng., Rhode Island Univ., Kingston, RI (Qing Yang; Weijun Xiao; Jin Ren)
Abstract	RAID architectures have been used for more than two decades to recover data upon disk failures. Disk failure is just one of the many causes of damaged data. Data can be damaged by virus attacks, user errors, defective software/firmware, hardware faults, and site failures. The risk of these types of data damage is far greater than disk failure with today's mature disk technology and networked information services. It has therefore become increasingly important for today's disk array to be able to recover data to any point in time when such a failure occurs. This paper presents a new disk array architecture that provides timely recovery to any point-in-time, referred to as TRAP-array. TRAP-array stores not only the data stripe upon a write to the array, but also the time-stamped exclusive-ORs of successive writes to each data block. By leveraging the exclusive-OR operations that are performed upon each block write in today's RAID4/5 controllers, TRAP does not incur noticeable performance overhead. More importantly, TRAP is able to recover data very quickly to any point-in-time upon data damage by tracing back the sequence and history of exclusive-ORs resulting from writes. What is interesting is that TRAP architecture is amazingly space-efficient. We have implemented a prototype TRAP architecture using software at block device level and carried out extensive performance measurements using TPC-C benchmark running on Oracle and Postgress databases, TPC-W running on MySQL database, and file system benchmarks running on Linux and Windows systems. Our experiments demonstrated that TRAP is not only able to recover data to any point-in-time very quickly upon a failure but it also uses less storage space than traditional daily differential backup/snapshot. Compared to the state-of-the-art continuous data protection technologies, TRAP saves disk storage space by one to two orders of magnitude with a simple and a fast encoding algorithm. From an architecture point of view, TRAP-array opens up another dimension for storage arrays. It is orthogonal and complementary to RAID in the sense that RAID protects data in the dimension along an array of physical disks while TRAP protects data in the dimension along the time sequence
Starting Page	289
Ending Page	301
File Size	379067
Page Count	13
File Format	PDF
ISBN	076952608X
ISSN	10636897
DOI	10.1109/ISCA.2006.44
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2006-06-17
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Computer architecture Space technology Protection Databases Computer errors Microprogramming Hardware History Software prototyping Software performance
Content Type	Text
Resource Type	Article

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