Hierarchical Storage Management

Developed By : Jaydeep Patel(13MCA63)

Kuldeep Patel(13MCA64)

Definition…• HSM is data storage technique, which automatically

moves data between high-cost and low-cost storage media.

• Mass storage-Multimedia Objects

• An application may actually use different types of media for different purposes .This approach is called hierarchical management

continue….. The primary goal of hierarchical storage is to route data to

the lowest cost devices that will support the required performance for that object.

A multimedia application requires storage for following functions:

• Disk cache or system memory cache

• Hard disk cache

• High speed disk storage

• Optical media and optical disc libraries

• Magnetic or optical tapes

Permanent vs. Transient storage issues

• Optical disk is used for permanent storage .They are considered a much safer storage than other.

• During life of multimedia object, it may be reside on one or all of the storage hierarchies.

• The process of moving data from one level of storage hierarchy to another is called migration.

• Migration of this objects to off-line media from on-line media is called archiving.

• Migration can be set up to be manual or automatic.

• In document imaging systems, compressed image files are created in magnetic cache areas on fast storage devices when documents are scanned.

• On completion of indexing and quality check they are moved to another magnetic storage area used for images accessed recently.

Optical Disk Library(Jukebox)

o An optical jukebox is a robotic data storage device that can automatically load and unload optical discs, such as Compact Disc, DVD, Ultra Density Optical or Blu-ray disc and can provide terabytes (TB) and petabytes (PB) of storage.

o The devices are often called optical disk libraries, robotic drives, or auto-changers.

o Jukebox can contain one or more drives.o The drives are daisy-chained on SCSI bus with their own SCSI Ids. The

robotics device also behaves as a SCSI device with its own SCSI ID thereby allowing programmatic control of the device.

o The size of jukeboxes varies from small desktop versions for the large from factors to full 19’’ rack versions(at least two racks are required) for the large from factors.

o A jukebox stack can carry 50-200 optical disks. With storage capacity of a single disk as high as 1 to 10 Gbytes, a jukebox cam store several terabytes of data.

How Jukebox Used?

o Jukebox is used for storing large volumes of multimedia information in one cost effective store.

o Jukebox-based optical disk libraries can be networked so that multiple users can access the information.

o For example it can be used as a document image server for all departmental documents.

Optical Disk Library Performanceo The best-case performance is achieved when the required information is in

an optical disk which is already mounted in a drive.

Optical Disk Library continue…

o The worst-case performance is when the required information is on a platter(disk volume) which is not mounted in a drive, and all drives have other mounted disk volumes.

o The disk access and transfer time are so small compared to the disk fetch and insertion time.

Hierarchical Storage Applications

1. Banks

2. Insurance Companies

3. Hospitals

4. State and Federal governments

5. Manufacturing companies

6. variety of other business and service organizations

Need to permanently store large volumes of their records, from simple documents to video information, for audit trail use.

o The WORM optical disks provide the most cost effective media that is almost on-line.

Best Examples of Multimedia Applications o Police records with fingerprints and mug-shots require

multimedia applications.

o Insurance companies can photograph or prepare video clips of vehicles and accident scenes and store them on optical disks.

o City and country governments use optical storage for maintaining near-line electronic databases of paper files on properties , tax records and dead recording.