Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1998-10-19
2001-08-07
Bragdon, Reginald G. (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C710S022000, C710S052000
Reexamination Certificate
active
06272591
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to RAID devices. More particularly, the present invention is directed to striping data on a RAID device using multiple virtual channels.
BACKGROUND OF THE INVENTION
Redundant Array of Inexpensive or Independent Disks (“RAID”) devices are an increasingly popular way to store large amounts of computer data. RAID devices typically consist of a RAID controller and multiple low capacity personal computer type disk drives that are bundled together to form a single high capacity drive. A RAID device is usually less expensive than conventional high capacity drives because the personal computer type drives are relatively inexpensive based on their high volume of production.
Because RAID devices include multiple disk drives, the probability that one of the drives will fail at any given time is relatively high. An issue with RAID devices is how to avoid the loss of data when one or more of the drives fail. One solution to this issue is to “stripe” a single data block across multiple disk drives in the RAID device. The data block is striped by breaking the block into multiple pieces or portions and storing each portion on a different disk drive. Frequently, parity information for the entire block is stored on one of the drives. If a single drive fails, the piece of the data block that was stored on the failed drive can be reassembled based on the remaining portions of the data block and the parity information stored on the other drives. U.S. Pat. No. 4,761,785 discloses an example of a RAID device that performs striping.
In most RAID devices, a host computer sends an entire data block in one piece to the RAID controller. The RAID controller must then partition the data block into multiple sub-blocks, calculate a parity block, and then write the sub-blocks and parity block to the disk drives. Because the RAID controller is required to perform all of these steps each time a data block is stored, the RAID controller causes some delay when data is stored on a RAID device. The delay can detrimentally slow the process of striping data on a RAID device.
Based on the foregoing, there is a need for an method and apparatus to more efficiently stripe data on a RAID device.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a RAID device for striping a data block across N disk drives. The RAID device receives a storage request from a host computer for the data block, and creates N virtual interface (“VI”) queue pairs. The queue pairs form N virtual channels to the host computer. Further, the RAID device posts a descriptor to each of the queue pairs, with each descriptor referring to 1/Nth of the data block. Further, the RAID device receives 1/Nth of the data block over each of the virtual channels and writes each received 1/Nth data block to a different one of the N disk drives.
REFERENCES:
patent: 5613071 (1997-03-01), Rankin et al.
patent: 6081848 (2000-06-01), Grun et al.
Dunning et al., “The Virtual Interface Architecture”, IEEE Micro, Mar.-Apr. 1998, vol. 18, issue 2, pp. 66-76.*
Intel and the VI Architecture: Frequently Asked Questions. [Retrieved Online May 11, 1998] URL: www.intel.com/p...rs/isv/vi/html/whats_VI/Vi_FAQ.htm.
Antonelli Terry Stout & Kraus LLP
Bragdon Reginald G.
Intel Corporation
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