Method and apparatus for guaranteeing average case disk transfer bandwidth and seek time for a video server
First Claim
1. A method for achieving substantially average case hard disk drive transfer bandwidth in a video server system having a plurality of D hard disk drives whereon blocks of video movies are stored before transfer to a buffer unit, the method comprising the following steps:
- (a) dividing each of said hard disk drives into Z substantially equal storage zones;
(b) recording a portion of each of said video movies across all of said storage zones such that each of said storage zones contains a substantially equal number of blocks of a video movie; and
(c) for said video server system, defining a substantially equal number of user streams per a slot using each of said zones, wherein a sum S of said user streams represents a maximum number of users that can access said video server system at one time;
wherein worst case bandwidth for each slot is determinable given worst case bandwidth information for transfers from each said zone.
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Accused Products
Abstract
In a video server hard disk storage unit, video layout ensures average case bandwidth and case seek time during bounded-time information transfers, to maximize access of users S. The storage unit includes D hard disks whose platters are divided into Z zones. Each movie is divided into i blocks and is striped across all D disks such that movie block i is stored on disk (i mod D). In one embodiment, movie block i is placed in zone (i/D) mod Z of disk (i mod D). User streams are organized into slots containing N=S/D streams and the number of streams in each slot accessing a zone is ≦(N/Z). Seeking is to the nearest end of a set of accesses, where total seek time for a set of N accesses is ≦N*seek (1.5/N). Preferably two storage buffers/stream are used. Admission policy permits stream assignment to any slot, but streams do not transfer until the needed data block is on the disk needed by the other streams in the slot, and until the block is in the proper disk zone. A second embodiment optimizes disk seeks by placing movie block i in zone (((i/D)+(i mod D)) mod Z) of disk (i mod D) to reduce buffer unit requirements. The S streams progress in order 0 to S-1 through disks 0 to D-1, all streams accessing each disk from the same zone before moving through the disk in another zone.
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Citations
27 Claims
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1. A method for achieving substantially average case hard disk drive transfer bandwidth in a video server system having a plurality of D hard disk drives whereon blocks of video movies are stored before transfer to a buffer unit, the method comprising the following steps:
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(a) dividing each of said hard disk drives into Z substantially equal storage zones; (b) recording a portion of each of said video movies across all of said storage zones such that each of said storage zones contains a substantially equal number of blocks of a video movie; and (c) for said video server system, defining a substantially equal number of user streams per a slot using each of said zones, wherein a sum S of said user streams represents a maximum number of users that can access said video server system at one time; wherein worst case bandwidth for each slot is determinable given worst case bandwidth information for transfers from each said zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for achieving substantially average case hard disk drive transfer bandwidth and substantially average case hard disk drive seek time in a video server system having a plurality of D hard disk drives whereon blocks of video movies are stored before transfer to a buffer unit and play-out to a plurality of users over a network, the method comprising the following steps:
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(a) dividing each of said hard disk drives into Z substantially equal storage zones; (b) recording, for each of said video movies, movie block i on hard disk drive (i mod D), and in zone ((i/D) mod Z) of hard disk drive (i mod D); (c) for said video server system, defining substantially N=S/D user streams/slot using each of said zones, wherein a sum S of said user streams represents a maximum number of users that can access said video server system at one time without substantial degradation of video server system performance; wherein worst case bandwidth for each slot is determinable given worst case bandwidth information for transfers from each said zone; and (d) seeking information from said D hard disk drives by seeking to a nearest end of a set of N ordered seeks, and then proceeding through said set to a nearest subsequent position; wherein substantially average case hard disk drive transfer seek time is achieved. - View Dependent Claims (16)
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17. A disk layout unit for use with a video server that stores video movies before they are output to a buffer on a plurality of D hard disk drives that are each divisible into Z substantially equal storage zones, each of said video movies being divisible into i blocks, the disk layout unit including:
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a mechanism causing each a portion of said video movies to be recorded across all of said storage zones such that each of said storage zones such that each of said storage zones contains a substantially equal number of blocks of a video movie; wherein a substantially equal number of user streams is defined per a slot using each of said zones, wherein a sum S of said user streams represents a maximum number of users that can access said video server system at one time; wherein worst case bandwidth for each slot is determinable given worst case bandwidth information for transfers from each said zone; and wherein substantially average case hard disk drive transfer seek time is achieved. - View Dependent Claims (18, 19, 20, 21)
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22. A system for achieving substantially average case hard disk drive transfer bandwidth in a video server system having a plurality of D hard disk drives, each divisible into Z substantially equal storage zones, whereon blocks of video movies are stored before transfer to a buffer unit, the system comprising:
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a disk layout unit causing a portion of each of said video movies to be recorded across all of said storage zones such that each of said storage zones contains a substantially equal number of blocks of a video movie; and an admission mechanism that defines a substantially equal number of user streams per a slot using each of said zones, wherein a sum S of said user streams represents a maximum number of users that can access said video server system at one time; wherein worst case bandwidth for each slot is determinable given worst case bandwidth information for transfers from each said zone. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification