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An algorithm for a restartable copy of data in a filesystem without loss of integrity

IP.com Disclosure Number: IPCOM000018584D
Original Publication Date: 2003-Jul-24
Included in the Prior Art Database: 2003-Jul-24
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Abstract

Disclosed is an algorithm for a restartable copy of data in a filesystem without loss of integrity.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 98% of the total text.

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An algorithm for a restartable copy of data in a filesystem without loss of integrity

   This invention solves the problem of being able to interrupt a filesystem data copy operation and restart without loss of integrity.

     The main idea here is to periodically note up to what point file was copied using a checkpoint and also note what contents were copied using a checksum. When the operation is resumed after the interruption consult the above stored data to restart. The main advantage of using this invention is customers don't have to schedule large amount of outages to copy data instead they can copy what ever the amount fits in their regular scheduled maintenance window and continue where it was left off in their next maintenance window.

     A file is divided into set of blocks. Data is copied block by block. During the file copy operation checksum is computed after every block copy. After every specified number of block copies all the information about the file metadata, number of blocks copied and the checksum of the file up to the number of blocks copied is recorded in a log file. This copy process can be interrupted any time. At the time of restart the algorithm reads the metadata and checksum from the log file and does a three way verification between the original file, partially copied file and log file to verify the integrity of the data. After verifying the integrity, algorithm resumes the copy from the file offset of last checkpoint.

Disclosed by International...