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.

Not peer-to-peer (P2P) model of media sharing. Large multimedia services Examples:

› Google Earth, YouTube, Facebook› CNN or Reuters.› Jukeboxes

Binary Large Objects (BLOBS) Single or mirrored disk systems. Overtly expensive,

› Rarely access content › Takes up the same amount of space

Multimedia Data › Graphics› Image› Animation› Video› Audio

Multimedia data is huge

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

MM DBMS

Temporal requirements › Has implications on their storage

Spatial constraints

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.

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 consider several issues

› 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

 

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.

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 [1] (45,000 Gbytes = 45 TeraBytes) [1].

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

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, robot-based, tertiary storage libraries.

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

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

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.

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

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 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

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

Example: On- Demand video services

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

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