Back to results
US 5,632,012 AGranted
Disk scrubbing system
AssigneeStorage Technology Corporation
InventorsJay S. Belsan, Alan R. Permut, George A. Rudeseal
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeStorage Technology Corporation
InventorsJay S. Belsan, Alan R. Permut, George A. Rudeseal
Estimating the term…
One or more background processes that references data storage volumes and cylinders that are to be scrubbed to ensure the integrity of the data stored thereon. A priority scrubbing process is also available to note data storage volumes that have recently had data written thereon by the host processor and which require a more timely review of the data than less frequently used volumes.
A data storage subsystem that receives data from at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, said logical partitions comprising dedicated partitions currently storing data and free partitions available to store data, said data storage subsystem comprising:
A data storage subsystem that receives data from at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, each of said logical partitions comprising at least two disk drives, said data storage subsystem comprising:
A method for correcting data errors in a data storage subsystem that receives data from at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, said logical partitions comprising dedicated partitions currently storing data and free partitions available for storing data, the method comprising the steps of:
A method for correcting data errors in a data storage subsystem that receives data from at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, said logical partitions comprising dedicated partitions currently storing data and free partitions available to store data, said method comprising the steps of:
A data storage subsystem that receives data for at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, said logical partitions comprising dedicated partitions currently storing data and free partitions available for storing data, said data storage subsystem comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's: parity data used in redundant arrays of…
Digital recording or reproducing: error detection or correction; Testing , e.g. of drop-outs
Error detection or correction; Testing , e.g. of drop-outs: by adding special lists or symbols to the coded information
Indexing scheme relating to G06F11/1076: scrubbing in RAID systems with parity
Term ended 24 Nov 2013 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to a data storage subsystem that dynamically and periodically reviews the integrity of the data records stored on the disk drive devices and reconstructs any corrupted data found thereon.
It is a problem in the field of computer systems to provide an inexpensive, high performance, high reliability memory that can both store large quantities of data and efficiently process changes to and create copies of the data records stored therein. One data storage subsystem used for this purpose makes use of a multiplicity of small form factor disk drives interconnected in a parallel array. The plurality of disk drives are divided into a number of redundancy groups, each of which includes a plurality of disk drives to spread the data transfers across all disk drives within the redundancy group rather than writing data to a single disk drive. A predetermined portion of the disk storage space in each redundancy group is used to store redundancy data to protect the integrity of the data stored in the redundancy group in the event of the failure of one or more of the physical disk drives included therein.
A significant difficulty with disk drive array data storage subsystems is that any read-after-write operation to ensure the integrity of the data that is written on to the disk drives of a redundancy group consumes a significant amount of data processing time and adversely impacts performance. The read-after-write operation occurs in synchronization with the write operation, implemented immediately after the write operation. If the host processor executes a number of successive writes to the same data record on the data storage subsystem, each write is immediately followed by a read-after-write operation. The interruption of successive write operations to perform a read-after-write adds a significant processing burden on the data storage subsystem. There is no capability to perform a single verification operation at the conclusion of the multiple successive write operations, even if the successive write operations function to write successive blocks of a single data file.
FIG. 1 illustrates in block diagram form the architecture of the disk drive array data storage subsystem;
FIG. 2 illustrates the cluster control of the data storage subsystem;
FIG. 3 illustrates the disk drive control circuits;
The data storage subsystem of the present invention uses a plurality of small form factor disk drives in place of a single large form factor disk drive to implement an inexpensive, high performance, high reliability disk drive memory that emulates the format and capability of large form factor disk drives. The plurality of disk drives in the disk drive array data storage subsystem are configured into a plurality of variable size redundancy groups of N+M connected disk drives to store data thereon. Each redundancy group, also called a logical disk drive, is divided into a number of logical cylinders, each containing i logical tracks, one logical track for each of the i physical tracks contained in a cylinder of one physical disk drive. Each logical track is comprised of N+M physical tracks, one physical track from each disk drive in the redundancy group. The N+M disk drives are used to store N data segments, one on each of N physical tracks per logical track, and to store M redundancy segments, one on each of M physical tracks per logical track in the redundancy group. The N+M disk drives in a redundancy group have unsynchronized spindles and loosely coupled actuators. The data is transferred to the disk drives via independent reads and writes since all disk drives operate independently. Furthermore, the M redundancy segments, for successive logical cylinders, are distributed across all the disk drives in the redundancy group rather than using dedicated redundancy disk drives.
The disk drive array data storage subsystem includes a controller that dynamically maps between three abstract layers: virtual, logical and physical. The virtual layer functions as a conventional large form factor disk drive memory. The logical layer functions as an array of storage units that are grouped into a plurality of redundancy groups, each containing N+M physical disk drives. The physical layer functions as a plurality of individual small form factor fixed block architecture (FBA) disk drives. The controller effectuates the dynamic mapping of data among these abstract layers and controls the allocation and management of the actual space on the physical devices. These data storage management functions are performed in a manner that renders the operation of the data storage subsystem transparent to the host processor, which perceives only the virtual image of the data storage subsystem.
The performance of this system is enhanced by the use of a cache memory with both volatile and non-volatile portions and "backend" data staging and destaging processes. Data received from the host processors is stored in the cache memory in the form of modifications to data already stored in the redundancy groups of the data storage subsystem. No data stored in a redundancy group is modified. A virtual track is staged from a redundancy group into cache. The host then modifies some, perhaps all, of the records on the virtual track. Then, as determined by cache replacement algorithms, the modified virtual track is selected to be destaged to a redundancy group. When thus selected, a virtual track is divided (marked off) into several physical sectors to be stored on one or more physical tracks of one or more logical tracks. A complete physical track may contain physical sectors from one or more virtual tracks. Each physical track is combined with N-1 other physical tracks to form the N data segments of a logical track.