Help Center/ Cloud Backup and Recovery/ User Guide/ Application-Consistent Backup/ What Is Application-Consistent Backup?
Updated on 2023-06-26 GMT+08:00
View PDF

What Is Application-Consistent Backup?

Overview

There are three types of backups in terms of backup consistency:

  • Inconsistent backup: An inconsistent backup contains data taken from different points in time. This typically occurs if changes are made to your files or disks during the backup. CBR cloud server backup uses the consistency snapshot technology for disks to protect data of ECSs and BMSs. If you back up multiple EVS disks separately, the backup time points of the EVS disks are different. As a result, the backup data of the EVS disks is inconsistent.
  • Crash-consistent backup: A crash-consistent backup captures all data on disks at the time of the backup and does not capture data in memory or any pending I/O operations. Although it cannot ensure application consistency, disks are checked by chkdsk upon operating system restart to restore damaged data and undo logs are used by databases to keep data consistent.
  • Application-consistent backup: An application-consistent backup captures data in memory or any pending I/O operations and allows applications to achieve a quiescent and consistent state.

Figure 1 compares these backup types in detail.

CBR supports both crash-consistent backup (also called cloud server backup) and application-consistent backup.

Crash-consistent backup does not back up data in memory or pending I/O operations and cannot be used to restore applications. If your server is running a MySQL or SAP HANA database, you can use application-consistent backup. An application-consistent backup capture application information both in memory and in pending I/O operations and can be used to quickly restore applications.

Figure 1 Backup consistency

Differences Between Application-Consistent Backup and Cloud Server Backup

Item

Application-Consistent Backup

Cloud Server Backup

Object

Cloud servers with MySQL or SAP HANA database deployed

Cloud servers without databases

Granularity

Cloud server

Cloud server

Vault

Server backup vault

Server backup vault

Recommended scenario

Data of cloud servers and their databases such as MySQL or SAP HANA database needs to be backed up. All data and application configurations need to be restored in case of an error.

Only data of cloud servers needs to be backed up. Such data needs to be restored in case of an error.

If cloud server backup is used to back up database servers, some database configurations may fail to be restored from the backups and issues may occur when the database is restarted.

There are two types of vaults to store server backups. Those store backups of non-database servers are server backup vaults, and those store backups of database servers are database server backup vaults.

Application Scope

Table 1 lists the OSs that support the installation of Agent.

Table 1 OSs that support installation of the Agent

Database

OS

Version

SQL Server 2008/2012/2019

Windows

Windows Server 2008, 2008 R2, 2012, 2012 R2, and 2019 for x86_64

SQL Server 2014/2016/Enterprise Edition

Windows

Windows Server 2014, 2014 R2, and 2016 Datacenter for x86_64

MySQL 5.5/5.6/5.7

Red Hat

Red Hat Enterprise Linux 6 and 7 for x86_64

SUSE

SUSE Linux Enterprise Server 11, 12, 15 SP1, 15 SP2 for x86_64

CentOS

CentOS 6 and 7 for x86_64

EulerOS

EulerOS 2.2 and 2.3 for x86_64

HANA 1.0/2.0

SUSE

SUSE Linux Enterprise Server 12 for x86_64

For the databases not included in this list, you can customize a script to perform application-consistent backup by referring to section "Using a Custom Script to Implement Application-Consistent Backup" in the Cloud Backup and Recovery Best Practices.

Process

Figure 2 shows the application-consistent backup process.

Figure 2 Application-consistent backup process
  1. Change the security group: Before performing an application-consistent backup task, change the security group of the server you want to back up. For details, see Changing a Security Group.
  2. Install the agent: Change the security group and install the agent in any sequence. Ensure that the two operations are completed before backing up the desired server. For details, see Installing the Agent.
  3. Create an application-consistent backup: After creating a server backup vault for storing application-consistent backups, associate it with the desired database server and then create an application-consistent backup. For details, see Creating an Application-Consistent Backup.
  4. Modify or compile a custom script: After backing up a database server on CBR Console, modify or compile a custom script on the database of the server. For details, see Using a Custom Script to Implement Application-Consistent Backup.
  5. Verify the backup result: After the backup is performed, verify that the backup succeeds. For details, see Verifying the Application-Consistent Backup Result.
  6. Use the backup to restore server data: Use the application-consistent backup to restore server data. The restored database applications and data are the same as those at the backup point in time. For details, see Restoring from a Cloud Server Backup.