Computer system and process for transferring streams of data between multiple storage units and multiple applications in a scalable and reliable manner

• US 20020162047A1
• Filed: 05/14/2002
• Published: 10/31/2002
• Est. Priority Date: 12/24/1997
• Status: Active Grant

• Current Assignee: Avid Technology Incorporated
• Original Assignee: Avid Technology Incorporated
• Inventors: Peters, Eric C., Rabinowitz, Stanley, Jacobs, Herbert R.
• Granted Patent: US 6,785,768 B2
• Time in Patent Office: Days
• US Class Current: 714/5
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 16/184 implemented as replicated file system
• CPC Class Codes: G06F 16/70 of video data
• CPC Class Codes: G06F 16/71 Indexing; Data structures therefor; Storage structures
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04N 21/2182 involving memory arrays, e.g. RAID disk arrays RAID arrays per se G06F3/0689; use of parity to protect data in RAID systems G06F11/1008
• CPC Class Codes: H04N 21/23103 using load balancing strategies, e.g. by placing or distributing content on different disks, different memories or different servers storage management G06F3/0604; allocation of resources considering the load in multiprogramming arrangements G06F9/505; techniques for rebalancing the load in a distributed system G06F9/5083; access to distributed or replicated servers, e.g. load balancing, in data networks H04L67/1001
• CPC Class Codes: H04N 21/23116 involving data replication, e.g. over plural servers synchronization of replicated data G06F11/1658; error detection or correction by means of data replication G06F11/2053; replication in distributed file systems G06F16/10; replication in distributed file systems G06F16/27; replication or mirroring of data in data networks H04L67/1095
• CPC Class Codes: H04N 21/2312 Data placement on disk arrays data placement in general G06F3/0604
• CPC Class Codes: H04N 21/2315 using interleaving
• CPC Class Codes: H04N 21/232 Content retrieval operation locally within server, e.g. reading video streams from disk arrays storage management G06F3/0604; details of querying and searching of video data from a database G06F16/739
• CPC Class Codes: H04N 21/2393 involving handling client requests scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/2396 characterized by admission policies admission control, resource allocation in open networks H04L12/5692; arrangements for network security using user profiles for access control H04L63/102; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/2405 : Monitoring of the internal components or processes of the server, e.g. server load allocation of resources in multiprogramming arrangements G06F9/50; performance measurement of computer activity G06F11/34
• CPC Class Codes: H04N 21/241 : Operating system [OS] processes, e.g. server setup
• CPC Class Codes: H04N 21/262 : Content or additional data distribution scheduling, e.g. sending additional data at off-peak times, updating software modules, calculating the carousel transmission frequency, delaying a video stream transmission, generating play-lists scheduling strategies for dispatcher in multiprogramming arrangements G06F9/4881; arrangements for scheduling broadcast services or broadcast-related services H04H60/06; flow control in packet networks H04L47/10; establishing a time schedule or organising the servicing of application requests H04L67/62
• CPC Class Codes: H04N 21/44004 : involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/442 : Monitoring of processes or resources, e.g. detecting the failure of a recording device, monitoring the downstream bandwidth, the number of times a movie has been viewed, the storage space available from the internal hard disk arrangements for monitoring broadcast services or broadcast-related services H04H60/29; arrangements for identifying or recognising characteristics with a direct linkage to broadcast information H04H60/35; monitoring of user activities for profile generation for accessing a video database G06F16/739; monitoring in wireless networks H04W24/00
• CPC Class Codes: H04N 21/47202 : for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/6581 : Reference data, e.g. a movie identifier for ordering a movie or a product identifier in a home shopping application
• CPC Class Codes: H04N 21/8456 : by decomposing the content in the time domain, e.g. in time segments
• CPC Class Codes: H04N 7/17336 : Handling of requests in head-ends
• CPC Class Codes: Y10S 707/99953 : Recoverability
• CPC Class Codes: Y10S 707/99956 : File allocation

Abstract

Multiple applications request data from multiple storage units over a computer network. The data is divided into segments and each segment is distributed randomly on one of several storage units, independent of the storage units on which other segments of the media data are stored. Redundancy information corresponding to each segment also is distributed randomly over the storage units. The redundancy information for a segment may be a copy of the segment, such that each segment is stored on at least two storage units. The redundancy information also may be based on two or more segments. This random distribution of segments of data and corresponding redundancy information improves both scalability and reliability. When a storage unit fails, its load is distributed evenly over to remaining storage units and its lost data may be recovered because of the redundancy information. When an application requests a selected segment of data, the request may be processed by the storage unit with the shortest queue of requests. Random fluctuations in the load applied by multiple applications on multiple storage units are balanced nearly equally over all of the storage units. Small data files also may be stored on storage units that combine small files into larger segments of data using a log structured file system. This combination of techniques results in a system which can transfer both multiple, independent high-bandwidth streams of data and small data files in a scalable manner in both directions between multiple applications and multiple storage units.

Claims

1. A data storage system, comprising:

a plurality of storage units;

a plurality of client systems, wherein each client system has a file system through which an application executed on the client system accesses data;

a network interconnecting the plurality of storage units and the plurality of client systems;

wherein the file system of each client system accesses data in one or more files using the plurality of storage units, wherein a file has a name and includes segments of data and redundancy information for each segment, wherein the redundancy information for a segment is one or more copies of the segment;

wherein the application executed on the client system accesses data in a file using a request to the file system indicating the name of the file;

wherein client code accessed by the file system in each client system includes means for writing data to a file comprising;

means for selecting, for each segment of the data, at least two of the storage units for storing the segment;

means for initiating a request to store each segment of the data to each of the at least two storage units selected for the segment, wherein the request includes an identifier of the segment; and

means for locally accessing information indicative of the at least two storage units on which each segment of a file is stored;

wherein each storage unit identifies a location on the storage unit for storing a received segment of data, stores the received segment of data at the identified location and maintains information associating the identifier of the segment of data with a location of each segment of data on the storage unit;

wherein client code accessed by the file system in each client system includes means for reading data from a file comprising;

means for selecting, for each segment of the requested data, one of the storage units on which the segment is stored using the locally accessed information indicative of the at least two storage units on which each segment of a file is stored; and

means for reading each segment of the requested data from the selected storage unit for the segment, including sending a request, for each segment, to the storage unit selected for the segment including the identifier of the segment; and

means for providing the read data to the application; and

wherein each storage unit retrieves a requested segment of data from the storage unit using the information associating the identifier of the segment of data with a location of each segment of data on the storage unit to obtain the location of the segment of data on the storage unit.

2. The data storage system of claim 1, wherein the means for reading each segment of the requested data includes means for scheduling data transfers over the network to efficiently utilize network bandwidth.

3. The data storage system of claim 1, wherein the means for reading each segment of the requested data comprises:

a plurality of buffers, wherein each buffer corresponds to a segment of the requested data;

means for ordering the buffers by a due time at the client and whether the requested data is expected to be available in a buffer at the storage unit; and

means for selecting a segment to be requested from a storage unit according to the ordering of the buffers.