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Tertiary Storage Systems: Solving Multimedia DBMS Storage Problems Greg Magsamen – September 27, 2007
Introduction Special Problems for Industries of Multimedia › On-Demand video, image and audio services must be able to provide content without bankrupting themselves with the special concerns. › Single Users can store content easily › Providers cannot To be a viable multimedia vendor, a useful storage system must be used to provide for multimedia database and serve multimedia content.
This Paper Not peer-to-peer (P 2 P) model of media sharing. Large multimedia services Examples: › Google Earth, You. Tube, Facebook › CNN or Reuters. › Jukeboxes
Everything on a Single Disks Binary Large Objects (BLOBS) Single or mirrored disk systems. Overtly expensive, › Rarely access content › Takes up the same amount of space
Multimedia Data: Its Nature Multimedia › Graphics › Image › Animation › Video › Audio Multimedia Data data is huge
MM DBMS At the heart of multimedia information systems lies the multimedia database management system. MM DBMS is a controlled collection of multimedia data items, › text, images, graphic objects, sketches, video, and audio. MM DBMS provides support for multimedia data types › plus facilities for the creation, storage, access, query, and control of the multimedia database Different data types involved in multimedia databases require special methods for › optimal storage › access, indexing, and retrieval
Multimedia data types Temporal requirements › Has implications on their storage Spatial constraints
Multimedia DBMS: Its Purpose Multimedia database management system › provides a suitable environment for using and managing multimedia database information › it must support the various multimedia data types › providing facilities for traditional DBMS functions The functions of a multimedia DBMS basically resemble those of a traditional DMBS New demands › specifically how to store the huge amounts of multimedia data in an enterprise size system.
Multimedia DBMS: Requirements Certain special requirements for the multimedia DBMS › › › › Traditional DBMS capabilities Huge capacity storage management Information retrieval capabilities Media integration, composition, and presentation Multimedia query support Multimedia interface and interactivity Performance In this paper the requirements of: › 1) Huge capacity storage management › 2) Information retrieval capabilities are addressed.
Multimedia storage systems › store and retrieve data from storage devices › manage related issues including data placement, scheduling, file management continuous data delivery, memory buffering, and pre-fetching Storage systems have long been viewed as a primary bottleneck for two reasons. › Multimedia applications have a much higher storage system load › Storage devices only marginally faster compared to increased processor and network performance This increasing speed mismatch has fueled a search for new storage structures and file system storage and retrieval mechanisms.
Administrators issues consider several › What kind of storage device to use › How to order the requests › Where to put data › How to manage memory › How to deal with overload situations
Storage Management: Huge Capacity The storage requirements Hierarchical storage places the multimedia data objects in a hierarchy of devices › online, near-line, or offline. › the highest level provides the highest performance, highest cost, smallest storage capacity, and least permanence › The permanence improves, however at significant additional cost, with the use of nonvolatile random access memory Cost and performance decrease as we go down the hierarchy, while storage capacity and permanence increase.
Highest level of storage is (volatile) random access memory (RAM) Followed by magnetic disk drives. › These provide online services. Optical storage devices provide the next level of storage. › They are near-line (like online jukeboxes) in most cases. The lowest level in the storage hierarchy represents offline storage devices › magnetic tapes, optical disks, and so forth. › These may or may not be directly connected to the computer.
Example of Needed Storage Huge volumes of data also characterize multimedia information. › Uncompressed video, for example a 10 -minute sequence at 30 frames per second, requires about 38 Gbytes of storage, reducible to about 3. 8 Gbytes with a compression ratio of 100: 1 › The potential for huge volumes of data Movie could run as long as two hours (45 Gbytes / movie) A typical video repository would house thousands of movies  (45, 000 Gbytes = 45 Tera. Bytes) .
Solving this? › A multimedia service will typically need to employ several secondary (e. g. , disk) and tertiary (e. g. , tapes, optical disks) storage devices to permanently store the data › A small amount of RAM is used to stage the data retrieved from disks and tapes before it is transmitted to clients
Tertiary Storage Systems: An Old Solution Storage of multimedia data is a critical issue High storage needs resulted in strengthening the role and importance of Tertiary Storage Systems (TSS Recent technological advances have resulted in wide availability of commercial products offering near-line, robotbased, tertiary storage libraries.
Why is HSS So Important? The preferred position is the use of hierarchical storage system (HSS), specifically the need for tertiary devices. › On top of the computer storage hierarchy is primary storage › Then magnetic disk devices, commonly identified as secondary storage. › At the bottom of the hierarchy are tertiary storage devices Tertiary storage includes magnetic tapes, optical disk devices and some ore recent technologies like optical tapes and holographic storage. From top to bottom of this hierarchy average access times increase, while the cost per megabyte of storage is dramatically decreased Therefore, tertiary storage is inexpensive but slow
Improvements However, recent advances in tertiary storage technology have made it of increasing interest › Increases in bits-per-inch and tracks-per inch densities have increased tape capability. › A variety of inexpensive tape drives have become available › Next the low cost of magnetic tape media, compared to that of magnetic disks › Robotic devices for handling magnetic tapes
Real World: Hierarchical Usage of Tertiary Storage The large enterprise sized multimedia systems addressed here need to capture, process, store, and maintain a variety of information sources These applications always include a multimedia database management system whose performance relies on the underlying storage system You can try to store all data on online magnetic disks › However, the huge amount of multimedia data makes this storage architecture neither practical nor economical.
HSS A multi-level hierarchical storage system (HSS) provides sufficient storage capacity at a more economical cost than disk only systems › invariably includes the long access latency of data held in tertiary storage devices deteriorating the performance of the storage system Multimedia objects can either be staged or pipelined from tertiary storage devices The balancing act must be continued and access algorithms are needed to retrieve multimedia in an efficient manner
DBMS and its Role of multimedia DBMS › manage and organize multimedia data stored at any level in the hierarchy › must have mechanisms for automatically migrating multimedia data objects from one level of the storage hierarchy to another › easily locate the specific device containing the multimedia data being sorted. Data migration in multilayered storage systems is not peculiar to multimedia DBMSs › All databases handling huge amounts of data must address this issue
Example: On- Demand video services In order to offer a wide variety of programs, a video system must accommodate a large number of video titles in a cost effective manner Traditionally, magnetic disks have been used in video servers to stream videos because of their high throughput, low access latency, and random data access This is the main reason why most of the previously proposed commercial video servers are based on magnetic disks
Magnetic Disks Magnetic disks are still not cost-effective to store a large volume of video files due to their relatively high cost On the other hand, low-cost tertiary storage is designed for mass storage in excess of terabytes However, due to their relatively long access latency, tertiary systems are not yet suitable for direct video streaming Therefore, a cost-effective approach is to make use of a hierarchical storage system In this system, the tertiary storage stores all video files which are dynamically transferred or “staged” onto the secondary level for streaming according to user demand
Example: On- Demand video services Such a hierarchical system is attractive › if many titles are not very popular This is particularly true for video-on-demand systems The disk space at the secondary level can be partitioned into two parts › the part storing those popular movies › the part for staging the not-so-popular ones
Conclusion: Multimedia Data in World Wide Web As web applications grow, the need for efficient and dependable multimedia databases will become essential Access to various large, visual multimedia databases over the Internet plays an increasingly important role Businesses increasingly provide and use services, applying formal (Web) services technology for the description, composition, and management of software as services
The Web is rapidly moving towards a platform for mass collaboration in content production and consumption Once thought outdated, hierarchical data storage systems, including tertiary storage should be the new paradigm in the multimedia database architecture In this paper it has been shown: › the architecture for multimedia databases should not rely on expensive single disks systems, but should employ the HSS model and make use of tertiary storage for reasons of costs and access
References  Donald A. Adjeroh, Kingsley C. Nwosu, "Multimedia Database Management—Requirements and Issues, " IEEE Multi. Media, vol. 04, no. 3, pp. 24 -33, Jul-Sept, 1997.  Vakali, Athena, Terzi, Evimaria, “Multimedia data storage and representation issues on tertiary storage subsystems: an overview”, ACM SIGOPS Operating Systems Review, Volume 35 , Issue 2, Pages: 61 – 77, April 2001.  S. -H. Gary Chan, Fouad A. Tobagi, "Modeling and Dimensioning Hierarchical Storage Systems for Low-Delay Video Services, " IEEE Transactions on Computers, vol. 52, no. 7, pp. 907 -919, Jul. , 2003.  Clement H. C. Leung, "Retrieving Multimedia Objects From Hierarchical Storage Systems, " mss, p. 297, Eighteenth IEEE Symposium on Mass Storage Systems and Technologies (MSS'01), 2001.  Yih-Farn Robin Chen, Giuseppe Di Fabbrizio, David Gibbon, Serban Jora, Bernard Renger, Bin Wei, “Geotracker: geospatial and temporal RSS navigation”, Proceedings of the 16 th international conference on World Wide Web WWW '07, SESSION: Smarter browsing, Pages: 41 – 50, May 2007.  Ozden, Banu, Rastogi, Rajeev, Silberschatz, Avi, “Architecture Issues in Multimedia Storage Systems”, ACM SIGMETRICS Performance Evaluation Review, Volume 25, Issue 2, pages 3 -12, Sept. 1997.  Stefan Tai, Nirmit Desai, Pietro Mazzoleni, “Service communities: applications and middleware”, Foundations of Software Engineering, Proceedings of the 6 th international workshop on Software engineering and middleware, SESSION: Networking and services, Pages: 17 – 22, 2006.  Grosky, William I. , “Managing multimedia information in database systems”, Communications of the ACM, Volume 40, Issue 12, pages 72 – 80, Dec. , 1997.  Pal Halvorsen, Carsten Griwodz, Vera Goebel, Ketil Lund, Thomas Plagemann, Jonathan Walpole, "Storage System Support for Continuous-Media Applications, Part 1: Requirements and Single-Disk Issues, " IEEE Distributed Systems Online, vol. 05, no. 1, Jan. 2004.  Oya Kalipsiz, "Multimedia Databases, " iv, p. 111, Fourth International Conference on Information Visualisation (IV'00), 2000