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Restoring Database from Physical Backup

Last updated: 2022-04-22 14:25:24

    Overview

    Note:

    In order to save the storage capacity, physical and logical backups in TencentDB for MySQL are to be compressed with qpress and then packed with xbstream offered by Percona.

    The open-source Percona XtraBackup can be used to back up and restore databases. This document describes how to use XtraBackup to restore a physical backup file of TencentDB for MySQL instance to a self-built database on CVM.

    Prerequisites

    Directions

    Note:

    This document takes a CVM instance running CentOS and a MySQL v5.7 instance as an example.

    Step 1. Download the backup file

    You can download data backups and log backups of TencentDB for MySQL instances in the console.

    Note:

    Each IP can have up to 10 download links by default, with a download speed limit of 20–30 Mbps each.

    1. Log in to the TencentDB for MySQL console. In the instance list, click an instance ID or Manage in the Operation column to enter the instance management page.
    2. On the Backup and Restoration > Data Backup List tab, locate the backup file to be downloaded and click Download in the Operation column.
    3. Copy the download address in the pop-up dialog box, log in to the Linux CVM in the same VPC as the TencentDB instance, and run wget to download the file over the high-speed private network.
      Note:

      • You can also click Download to download it directly. However, this may take longer.
      • wget command format: wget -c 'backup file download address' -O custom filename.xb
      The example is as follows:
      wget -c 'https://mysql-database-backup-sh-1218.cos.ap-nanjing.myqcloud.com/12427%2Fmysql%2F0674-ffba-11e9-b592-70bd%2Fdata%2Fautomatic-delete%2F2019-12-03%2Fautomatic%2Fxtrabackup%2Fbk_61_156758150%2Fcdb-293fl9ya_backup_20191203000202.xb?sign=q-sign-algorithm%3Dsha1%26q-ak%3DAKzxfbLJ1%26q-sign-time%3D1575374119%3B1575417319%26q-key-time%3D1575374119%3B1575417319%26q-header-list%3D%26q-url-param-list%3D%26q-signature%3Dba959757&response-content-disposition=attachment%3Bfilename%3D%22yuan177685_backup_20191203000202.xb%22&response-content-type=application%2Foctet-stream' -O /data/test.xb
      

    Step 2. Restore data

    2.1 Unpack the backup file

    Run the xbstream command to unpack the backup file to the target directory.

    xbstream -x --parallel=2  -C /data/mysql < /data/test.xb
    
    Note:

    • The target directory /data/mysql is used as an example in this document. You can replace it with the directory you actually use to store the backup file.
    • Replace /data/test.xb with your backup file.

    The unpacking result is as shown below:
    extract.png

    2.2 Decompress the backup file

    1. Download qpress by running the following command:
      wget -d --user-agent="Mozilla/5.0 (Windows NT x.y; rv:10.0) Gecko/20100101 Firefox/10.0 http://www.quicklz.com/qpress-11-linux-x64.tar
      
    Note:

    If an error is displayed during the wget download, you can go to QuickLZ's official website to download qpress locally and upload it to the Linux CVM instance. For more information, see Uploading Files from Linux or MacOS to Linux CVM via SCP.

    1. Extract the qpress binary files by running the following command.

      tar -xf qpress-11-linux-x64.tar -C /usr/local/bin
      source /etc/profile
      
    2. Decompress all .qp files in the destination directory by running the following qpress command:

      xtrabackup --decompress --target-dir=/data/mysql
      
    Note:

    • /data/mysql is the target directory where the backup file was previously stored. You can replace it with the directory you actually use.
    • The --remove-original option is supported only in Percona Xtrabackup v2.4.6 and later.
    • xtrabackup won't delete the original files during decompression by default. If you want to delete them upon the completion of decompression, add the --remove-original parameter to the above command.

    decompress.png

    2.3 Prepare the backup file

    After a backup file is decompressed, you need to execute the "apply log" operation by running the following command.

    xtrabackup --prepare  --target-dir=/data/mysql
    

    If the execution result contains the following output, it means that the preparation succeeded.
    prepare.png

    2.4 Modify the configuration file

    1. Run the following command to open the backup-my.cnf file.
      vi /data/mysql/backup-my.cnf
      
    Note:

    The target directory /data/mysql is used as an example in this document. You can replace it with the directory you actually use.

    1. Given the existing version issues, the following parameters need to be commented out from the extracted file backup-my.cnf.
    • innodb_checksum_algorithm

    • innodb_log_checksum_algorithm

    • innodb_fast_checksum

    • innodb_page_size

    • innodb_log_block_size

    • redo_log_version

    2.5 Modify file attributes

    Modify file attributes and check whether files are owned by the mysql user.

    chown -R mysql:mysql /data/mysql
    

    Step 3. Start the mysqld process and log in for verification

    1. Start the mysqld process.

      mysqld_safe --defaults-file=/data/mysql/backup-my.cnf --user=mysql --datadir=/data/mysql &
      
    2. Log in to the client for verification.

      mysql  -uroot
      

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