Patent ID: 8719668
Filing Date: 2014-05-06
Classification: G06F

Abstract:
1. A nonvolatile storage system, comprising: multiple nonvolatile storage media; and at least one media controller, which is coupled to the multiple nonvolatile storage media, wherein the media controller includes: wherein the error probability is a probability that data within the unit physical area are incorrect, and is a prior probability or a number of corrected bits per data size when the data stored in the unit physical area are read in past time, and wherein the media controller is configured to, in a data read process: (A) read data from a read-source physical area in a read-source nonvolatile storage medium; (B) identify from the management information an error probability, which is the error probability of a unit physical area including the read-source physical area and is better suited to a state of the read source in the current read process than the error probability identified for the same unit physical area in a past read process; and (C) use the error probability identified in (B) to correct the data read in (A) using the error correcting circuit; and further comprising: multiple nonvolatile storage devices configuring a RAID group; and a storage controller, which is coupled to the multiple nonvolatile storage devices, wherein each of the multiple nonvolatile storage devices has one of the multiple nonvolatile storage media and the media controller, wherein the storage controller is coupled to multiple media controllers in the multiple nonvolatile storage devices, and wherein (a) a read-source nonvolatile storage device is configured to detect that correcting the data in (C) has failed and there is an error that cannot be corrected, wherein the read-source nonvolatile storage device among the multiple nonvolatile storage devices is a read-source of the data read in (A), and wherein a read-source media controller is the media controller in the read-source nonvolatile storage device, (b) wherein the read-source media controller is configured to send failure occurrence information denoting that a failure has occurred to the storage controller, (c) wherein the read-source media controller is configured to send free information denoting whether or not there is a free physical area in the one of the multiple nonvolatile storage media in the read-source nonvolatile storage device to the storage controller, (d) the storage controller is configured to receive the free information, (e) the storage controller is configured to determine whether or not the free information denotes the existence of the free physical area, and (f) in a case where the result of the determination in (e) is affirmative, the storage controller is configured to read data from nonvolatile storage devices in the RAID group other than the read-source nonvolatile storage device, construct data stored in the read-source nonvolatile storage device based on the data that have been read, and send the constructed data to the read-source nonvolatile storage device, in accordance with which the constructed data are stored in the free physical area of the read-source nonvolatile storage device; wherein the storage controller is configured to, upon receiving the failure occurrence information, send a failure information request to the read-source nonvolatile storage device, the read-source nonvolatile storage device is configured to, in response to this request, send failure information and the free information to the storage controller so that the storage controller is able to receive the failure information and the free information in (d), and the failure information includes information denoting the read-source nonvolatile storage medium of the data with the uncorrectable error.