Abstract: In a storage system having a plurality of disks arranged in a RAID array with one of the disks failed, a method of reorganizing the data on the RAID array at the time of failure to prevent both a decrease in performance of the array and reliability of the data and an increase in the cost of operation. Data from the failed disk is regenerated one strip at a time and written onto the original parity chunk for the strip. The resulting fully folded array has the characteristics of a RAID level 0 array. When a replacement disk is inserted into the array the process is reversed to bring the fully folded array back to a fully redundant condition.
Abstract: A Faraday shield minimizes the leakage of electromagnetic interference (EMI) and radio frequency interference (RFI) of a maximum frequency and corresponding wavelength that emanates from electronic components contained within the shield. The top and bottom each contain apertures that are dimensioned to effectively block the escape of EMI and RFI from the shield and to permit the flow of air to dissipate heat without generating acoustic noise. The thickness of the top of the shield is at least one half of the diagonal length across the largest of the apertures located in the top. The length of the longest aperture side is less than one fourth of the wavelength of the maximum frequency of EMI and RFI contained by the shield. Corresponding relationships exist between the apertures located in the shield bottom and its thickness.
Type:
Grant
Filed:
November 28, 1994
Date of Patent:
July 9, 1996
Assignee:
Digital Equipment Corporation
Inventors:
William F. McCarthy, Colin E. Brench, Daniel M. Snow
Abstract: Ideal for use in high-speed wide-area networks, such as HDLC as defined in ISO Standard 3309, a strong framing method for data packets significantly improves undetected error probability. In a run-length code type data communication scheme, wherein frame delimiter strings, abort strings and idle strings, are transmitted as control symbols, the method includes providing the frame delimiter string as a multi-symbol construct for delimiting the transmitted data, providing the abort strings and idle strings to respectively include minimum run lengths which are substantially longer than the individual symbols in the multi-symbol construct, transmitting data with control symbols as a bit sequence, and receiving and analyzing the transmitted data at the data-receiving device to detect the presence of bit errors.
Abstract: The present invention senses angular acceleration of a Head Disk Assembly ("HDA") in a disk drive servo system and provides an acceleration feedback signal. A filter network filters the acceleration feedback signal and supplies a filtered signal for nullifying tracking error caused by shock, vibration and windup disturbances to the system.