Electrical computers and digital processing systems: multicomput – Remote data accessing – Accessing a remote server
Reexamination Certificate
1999-07-29
2001-09-11
Geckil, Mehmet B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Remote data accessing
Accessing a remote server
C709S203000, C711S114000
Reexamination Certificate
active
06289376
ABSTRACT:
The present invention relates to a storage server for retrieving data from a plurality of disks in response to user access requests. In particular, the invention relates to a multi-processing architecture in which a plurality of processors are coupled to disjoint subsets of disks, and a non-blocking cross bar switch routes data from the processors to users.
BACKGROUND OF THE DISCLOSURE
A storage server allows users to efficiently retrieve information from large volumes of data stored on a plurality of disks. For example, a video-on-demand server is a storage server that accepts user requests to view a particular movie from a video library, retrieves the requested program from disk, and delivers the program to the appropriate user(s). In order to provide high performance, storage servers may employ a plurality of processors connected to the disks, allowing the server to service multiple user requests simultaneously. In such multi-processor servers, processors issue commands to any of the disks, and a multi-port switch connecting the processors to the disks routes these commands to the appropriate disk. Data retrieved from disk is similarly routed back to the appropriate processor via the switch. Such servers use non-deterministic data routing channels for routing data. To facilitate accurate data retrieval, these channels require a sub-system to arbitrate conflicts that arise during data routing.
There are a number of problems, however, associated with such multi-processor servers. First, the switch becomes a major source of latency. Since all data exchanged between the processors and disks pass through the switch and the data must be correctly routed to the appropriate destination, certain overhead processes must be accomplished to arbitrate routing conflicts and handle command and control issues. These overhead requirements cause a delay in data routing that produces data delivery latency. While it is possible to reduce such latency by reserving extra channel bandwidth, this approach dramatically increases the cost of the server. Second, the server is required to store all user requested data in a cache prior to delivery. Such a caching technique leads to poor cache efficiency wherein multiple copies of the same user data is stored in cache. These problems can significantly degrade the disk bandwidth and performance provided by the server, thereby limiting the number of users that can be supported by a given number of processors and disks. In commercial applications such as video-on-demand servers, however, it is imperative to maximize the number of users that can be supported by the server in order to achieve a reasonable cost-per-user such that the servers are economically viable.
Therefore, there is a need in the art for a multi-processor storage server that can service multiple access requests simultaneously, while avoiding the congestion, overhead, and disk scheduling bottlenecks that plague current systems.
SUMMARY OF THE INVENTION
The disadvantages associated with the prior art are overcome by a server comprising a plurality of server modules, each containing a single processor, that connect a plurality of Fiber Channel disk drive loops to a non-blocking cross bar switch such that deterministic data channels are formed connecting a user to a data source. Each server module is responsible for outputting data at the correct time, and with the proper format for delivery to the users. A non-blocking packet switch routes the data to a proper output of the server for delivery to users. Each server module supports a plurality of Fiber Channel loops. The module manages data on the disks, performs disk scheduling, services user access requests, stripes data across the disks coupled to its loop(s) and manages content introduction and migration. Since the server module processors never communicate with any disks connected to other processor modules, there is no processor overhead or time wasted arbitrating for control of the Fiber Channel loops. As a result, the server can make the most efficient use of available bandwidth by keeping the disks constantly busy.
The server modules transfer data read from the Fiber Channel loops to the non-blocking packet switch at the appropriate output rate. The packet switch then outputs data to a plurality of digital video modulators that distribute the data to requesting users. Data requests from the users are demodulated and coupled to the switch. The switch routes the requests to the server controller which in turn routes the requests to an appropriate server module that contains the requested data. In this manner, a user establishes a deterministic channel from their terminal (decoder) to the data source (disk drive) such that low latency data streaming is established.
REFERENCES:
patent: 4888691 (1989-12-01), George et al.
patent: 5220653 (1993-06-01), Miro
patent: 5446855 (1995-08-01), Dang et al.
patent: 5603063 (1997-02-01), Au
patent: 5617425 (1997-04-01), Anderson
patent: 5644786 (1997-07-01), Gallagher et al.
patent: 5671377 (1997-09-01), Bleidt et al.
patent: 5694615 (1997-12-01), Thaper et al.
patent: 5737549 (1998-04-01), Hersch et al.
patent: 5742599 (1998-04-01), Lin et al.
patent: 5790775 (1998-08-01), Marks et al.
patent: 5815662 (1998-09-01), Ong
patent: 5862313 (1999-01-01), Johnson et al.
patent: 5862403 (1999-01-01), Kanai et al.
patent: 5892913 (1999-04-01), Adiga et al.
patent: 5922077 (1999-07-01), Espy et al.
patent: 5923839 (1999-07-01), Munetoh et al.
patent: 5996014 (1999-11-01), Uchirori et al.
patent: 6000020 (1999-12-01), Chin et al.
patent: 6070251 (2000-05-01), Chong
patent: 6076105 (2000-06-01), Wolif
Ashley William
Chin Danny
Lerman Jesse S.
Taylor Clement G.
Zack Steven
DIVA Systems Corp.
Geckil Mehmet B.
Thomason Moser & Patterson LLP
LandOfFree
Tightly-coupled disk-to-CPU storage server does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tightly-coupled disk-to-CPU storage server, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tightly-coupled disk-to-CPU storage server will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2543737