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Method for logging metadata in logical file system

A logic file and metadata technology, applied in electrical digital data processing, special data processing applications, instruments, etc., can solve problems such as inability to solve file metadata consistency, and achieve the effect of reducing time

Inactive Publication Date: 2011-04-20
DAWNING INFORMATION IND BEIJING
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AI Technical Summary

Problems solved by technology

The traditional file system cannot solve the requirement of file metadata consistency under this distributed / parallel file system

Method used

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  • Method for logging metadata in logical file system
  • Method for logging metadata in logical file system
  • Method for logging metadata in logical file system

Examples

Experimental program
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Embodiment Construction

[0015] Metadata Request Processing Process

[0016] The metadata access process is attached figure 2 , when a user requests metadata, the service thread first writes it to the log cache, and writes it to the log device, and then modifies the metadata cache. When the amount of metadata in the log cache reaches a certain level, write the data in the log cache back to the disk, and then clear the data on the log device.

[0017] Metadata recovery process

[0018] When the data in the log cache is written back to the disk, when a system failure occurs, after restarting, the metadata needs to be restored. The process is as follows: picture three. Create redo and undo teams in memory respectively: when the metadata operation is completely recorded on the log device, put the metadata operation into the redo queue; if the metadata operation is incompletely recorded on the log device, put the Metadata operations are put into the undo queue. Then, modify the corresponding metadata...

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Abstract

The invention provides a method for logging metadata in a logical file system. Logs are saved in a region with fixed size, and a memory structure is fully utilized for reducing the writing times of a permanent device; only data before and after modifying the metadata is precisely recorded during the operation process of the metadata, so that the recovery process does not depend on codes of the file system; the logs are brushed to the permanent device before the modification result is returned to a user; when in recovery, the re-operation or the cancellation of the operation is carried out according to log data only, thereby ensuring that the metadata is in the consistent state. The memory structure is fully utilized for reducing the writing times of the permanent device (a logging device); only the data before and after modifying the metadata is precisely recorded during the operation process of the metadata, so that the recovery process does not depend on codes of the file system; when in recovery, the re-operation or the cancellation of the operation is carried out according to the log data only, thereby ensuring that the metadata is in the consistent state and reducing the time required for recovery.

Description

technical field [0001] The invention relates to the technical field of computer storage systems, in particular to a log method for logical file system metadata. Background technique [0002] File metadata is the core data of the computer operating system and is related to the reliability of the storage system. The general file system provides tools such as fsck to check and repair the consistency of the file system. The duration of this process is proportional to the size of the file system, so large file systems take a long time to repair. Some file systems (such as Ext3 / 4 specially developed for Linux) rely on journal technology to greatly shorten the recovery time. However, these file systems only solve the problem of file metadata consistency on local disks. In a large-scale distributed system, such as a distributed environment with hundreds or thousands of nodes, in this case, in order to improve the reliability of the system, it is necessary to use a dedicated stora...

Claims

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Application Information

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IPC IPC(8): G06F17/30
Inventor 王勇张东阳张玉龙苗艳超
Owner DAWNING INFORMATION IND BEIJING
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