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    Data Online Migration:Background information

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    Data Online Migration:Background information

    最終更新日:Oct 31, 2024

    This topic describes how to migrate data from local file systems to Alibaba Cloud Object Storage Service (OSS).

    Overview

    Alibaba Cloud Data Online Migration provides a data migration channel between different storage services. Data Online Migration can be used to migrate data from third-party storage services to OSS, between local file systems and OSS, between local file systems, or between OSS buckets.

    To use Data Online Migration, you need to only log on to the Data Online Migration console, create a source data address and a destination data address, and then create a migration task. After the migration task starts, you can manage the task in the console. For example, you can view the progress and traffic information of the task.

    Introduction to local file systems

    Local file systems are classified into the following types:

    • File system that is deployed on a local computer to manage and store files on the local computer

    • File system that is mounted to a local computer, such as an File Storage NAS (NAS) or Google File System (GFS) file system

    A local file system on the Linux operating system supports a variety of functions. The following table describes the common functions.

    Function type

    Description

    File I/O

    A local file system supports Portable Operating System Interface (POSIX)-based file I/O functions such as open, read, write, lseek, and close. You can use these functions to read and write files.

    Directory operation

    A local file system supports directory operation functions such as opendir, readdir, and closedir. You can use these functions to read and manage files in directories.

    File metadata

    A local file system supports file metadata functions such as stat, fstat, chown, chmod, and utimes. You can use these functions to obtain and modify the metadata information of files.

    Memory mapping

    A local file system allows you to use the mmap function to map files to the address space of processes and then perform I/O operations on memory.

    File locking

    A local file system allows you to use the fcntl function to lock and unlock files. This ensures data consistency during concurrent access by multiple processes.

    File system cache

    A local file system allows you to refresh data in the cache of the file system by using functions such as sync and fsync. This helps you write data to disks.

    In addition to the preceding functions, functions such as file I/O vectoring functions (readv and writev), file system event function (inotify), and POSIX message queue functions (mq_open, mq_send, and mq_receive) are also supported by local file systems. The functions and features supported by a local file system vary with the type and version of the file system. Therefore, you must understand the file system that you use and select appropriate functions based on your business requirements.

    Flowcharts

    Migrate data

    The following figure shows the process of migrating data from local file systems to OSS.

    image.png

    Create a migration task

    The following figure shows the process of creating a migration task.创建代理任务.jpg

    Important

    When you create a data address for a local file system, you must associate the data address with an agent.

    References