Overview of physical backup and restore

Backup and restore is a core component of the high availability feature of OceanBase Database. It is mainly used to ensure data security, including preventing storage media damage and user errors. If data is lost due to storage media damage or user errors, you can restore the data by using the restore feature.

Overview

The backup and restore module of OceanBase Database provides features such as backup, backup verification, restore, and cleanup.

Backup

OceanBase Database supports tenant-level physical backup. A physical backup consists of data backup and log archiving. Therefore, the physical backup feature is a combination of data backup and log archiving. Here, a tenant refers to a user tenant. Physical backup is not supported for the sys tenant or the Meta tenant.

Data backup refers to the feature of backing up data. This feature is divided into full backup and incremental backup:

• Full backup refers to backing up all macroblocks.

• Incremental backup refers to backing up macroblocks added or modified since the last backup.

The data backed up by data backup includes the following:

• Information about the tenant, including the tenant name, cluster name, time zone (timezone), replica distribution (locality), and compatibility mode (MySQL or Oracle) of the tenant.

• All user table data

  Note

  Data backup backs up system variables and tenant-level configuration items, but does not back up cluster-level configuration items or private system table data.

Log archiving refers to the automatic archiving of log data. OBServer nodes periodically archive log data to the specified backup path. This process is fully automatic and does not require external triggering. After the log archiving service is enabled, the data dictionary is also archived.

Backup verification

The backup verification feature of OceanBase Database is mainly used to solve the problems of the integrity and correctness of backup and archive data. You can actively verify whether the backup set and archive logs are missing files, have physical data damage, or logical inconsistencies without performing actual restore operations.

Backup verification is divided into Basic verification and Physical verification based on the verification level. Specifically:

• Basic verification: only checks the completeness of the file list.

• Physical verification: checks the correctness and logical consistency of physical data.

Backup verification supports verification at different granularities, including verification of the entire backup and archive path, verification of specified backup sets or log archive pieces, and verification of specified paths across clusters.

Restore

The overall architecture of physical restore is as follows:

1. Physical restore supports tenant-level restore and table-level restore.

   • Tenant-level restore: Tenant-level restore is the process of rebuilding a new tenant based on the existing data backup. Tenant-level restore ensures global consistency across tables and partitions.

   • Table-level restore: Table-level restore is the process of restoring a user-specified table from the backup data to an existing tenant. The existing tenant can be the same as the original tenant, a different tenant within the same cluster, or a tenant in a different cluster.

2. Tenant-level restore supports full restore and quick restore.

   Notice

   After a tenant is restored by using quick restore, the tenant cannot be manually merged, cannot be backed up, and cannot be switched to or failover to the primary database. The tenant can only exist as a standby database.

   • Full restore: Full restore refers to restoring macroblock data and incremental logs. After all data is restored from the backup media to the local environment, the restored tenant can provide services. The full restore process includes the restore and recover processes for tenant system tables and user tables. Restore refers to restoring the baseline data required for the restore to the OBServer node of the target tenant. Recover refers to restoring the logs corresponding to the baseline to the corresponding OBServer node.

   • Quick restore: Quick restore refers to providing services to users without restoring macroblock data. This reduces the restore waiting time and lowers the user's usage cost.

3. Select the restore time point for your physical restore.

   • Complete restore: No restore timestamp is specified.

   • Incomplete restore with a specified SCN or timestamp: SCN is the precise version number of OceanBase Database. In Oracle-compatible mode, the timestamp is precise to the nanosecond, with no precision loss. In MySQL-compatible mode, the timestamp is precise to the microsecond, with precision loss after the microsecond.

For more information about the physical restore process, see Restore process.

Cleanup

OceanBase Database provides automatic and manual cleanup capabilities for backup data, so that you can flexibly handle different business scenarios.

• Automatic cleanup: An automatic cleanup mechanism based on the recovery window (recovery_window). After you set the expiration time for backup data, the system periodically triggers cleanup tasks to remove expired backup sets and data archive pieces.

• Manual cleanup: Manual cleanup is divided into two types. The first type is manual cleanup of specified backup sets or log archive pieces. The second type is manual cleanup of all backup sets or data archive pieces in the entire path (data backup path or log archive path).

Backup media requirements

OceanBase Database of the current version supports backup media such as Alibaba Cloud OSS, NFS, Azure Blob, AWS S3, and object storage services that are compatible with the S3 protocol (such as Huawei OBS, Google GCS, and Tencent Cloud COS). Some of these backup media require meeting certain basic requirements before they can be used.

SDK version requirements

In the current version, obdal is used by default to access object storage. obdal is a unified framework for object storage developed based on OpenDAL. For more information about OpenDAL, see OpenDAL.

In addition, if you want to use the SDK of an object storage service, the version of the object storage service's SDK must correspond to the version of the observer component. The following table describes the correspondence between the versions of the object storage service's SDK and the observer component.

Interface requirements

• Alibaba Cloud OSS:

  • The following table describes the interfaces supported by Alibaba Cloud OSS.

    Interface name	Description
    PutObject	Uploads a single object.
    DeleteObject	Deletes a single object.
    DeleteObjects	Deletes objects in batches.
    GetObject	Retrieves an object.
    ListObjects	Lists all objects in the storage space (strong consistency is required).
    HeadObject	Retrieves the metadata of an object.
    AppendObject	Uploads an object in append mode.
    PutObjectTagging (optional)	Sets or updates the tags of an object.
    GetObjectTagging (optional)	Retrieves the tags of an object.
    InitiateMultipartUpload	Initializes a multipart upload.
    UploadPart	Uploads a part.
    CompleteMultipartUpload	Merges the uploaded parts into one object.
    AbortMultipartUpload	Aborts a multipart upload and deletes the uploaded parts.
    ListMultipartUploads	Lists the information of initialized but not completed or not terminated multipart uploads.
    ListParts	Lists the uploaded parts in an upload task.

  • Only the V1 signature algorithm is supported.

• NFS: The version must be NFS 3 or later.

• Object storage services compatible with the S3 protocol (for example, Huawei OBS, Google GCS, and Tencent Cloud COS):

  1. The following table describes the S3 APIs that must be supported.

     Interface name	Description
     PutObject	Uploads a single object.
     DeleteObject	Deletes a single object.
     DeleteObjects	Deletes objects in batches.
     GetObject	Downloads a single object.
     ListObjects	Lists all objects under the specified path.
     HeadObject	Retrieves the metadata of an object.
     PutObjectTagging (optional)	Sets the tags of an object.
     GetObjectTagging (optional)	Retrieves the tags of an object.
     CreateMultipartUpload	Initializes a multipart upload.
     UploadPart	Uploads a single part.
     CompleteMultipartUpload	Merges the uploaded parts into one object.
     AbortMultipartUpload	Aborts a multipart upload and deletes the uploaded parts.
     ListMultipartUploads	Lists the uploaded parts.
     ListParts	Lists the uploaded parts in an upload task.

  2. The object access URL must support the virtual-hosted-style access method. For more information about virtual-hosted-style requests, see AWS S3 documentation.

Before you select a backup media, you can run the test_io_device command in the ob_admin tool to verify whether the I/O interfaces and I/O permissions provided by the backup media meet the requirements for backup and restore. You can also run the io_adapter_benchmark command in the ob_admin tool to view the read and write performance between an OBServer node and the backup media, which can be used as a reference for backup performance. For more information about the test_io_device and io_adapter_benchmark commands, see test_io_device and io_adapter_benchmark.

Directory structure

Data backup directory

The directories created by the data backup feature at the backup destination and the types of files stored in each directory are as follows:

data_backup_dest
├── format.obbak                                            // Formatted information of the backup path
├── check_file
│   └── 1002_connect_file_20230111T193020.obbak             // Connectivity check file
├── backup_sets                                             // A summary directory of the data backup list, which records the list of all data backup sets
│   ├── backup_set_1_full_end_success_20230111T193420.obbak // Placeholder for the end of a full backup
│   ├── backup_set_1_full_start.obbak                       // Placeholder for the start of a full backup
│   ├── backup_set_2_inc_start.obbak                        // Placeholder for the start of an incremental backup
│   └── backup_set_2_inc_end_success_20230111T194420.obbak  // Placeholder for the end of an incremental backup
└── backup_set_1_full                                        // A full backup set. A name ending with full indicates a full backup, and inc indicates an incremental backup.
    ├── file_list.0.obbak
    ├── backup_set_1_full_20230111T193330_20230111T193420.obbak // Placeholder that shows the start and end times of the full backup
    ├── single_backup_set_info.obbak                        // Metadata of the current backup set
    ├── tenant_backup_set_infos.obbak                       // Information about the full backup sets of the current tenant
    ├── infos
    ├── logstream_1                                          // Log stream 1
    └── logstream_1001                                       // Log stream 1001

In the data backup directory, the top-level directory contains the following three types of data:

• format.obbak: used to record the metadata of the backup path.

• check_file: used for connectivity check of the user data backup directory.

• backup_sets: a summary directory of the list of data backup sets, which records the list of all data backup sets.

• backup_set_1_full: the directory indicates a data backup set. backup_set_1 indicates that the backup_set_id of the backup set is 1. If the directory name ends with full, it indicates a full backup. If it ends with inc, it indicates an incremental backup. A backup set is generated for each data backup. After the data backup is completed, the backup set will no longer be modified.

  A data backup set mainly contains the following data:

  • file_list.0.obbak: this file records the files and directories contained in the current directory.

  • backup_set_1_full_20230111T193330_20230111T193420.obbak: this file shows the ID, start time, and end time of the current backup set. This file is only for information display.

  • single_backup_set_info.obbak: this file records the metadata of the current backup set, including the backup point and the dependent logs.

  • tenant_backup_set_infos.obbak: this file records the metadata of all existing backup sets of the current tenant.

  • infos: this directory records the metadata of the data backup set.

  • logstream_1: this directory records all data of log stream 1. Log stream 1 is the system log stream of the OceanBase Database tenant.

  • logstream_1001: this directory records all data of log stream 1001. Log streams with numbers greater than 1000 are the user log streams of the OceanBase Database tenant.

Cluster-level configuration item backup directory

Each time a backup of cluster-level configuration items is initiated, the system generates a backup file of the cluster-level configuration items in the specified directory. The directory structure is as follows:

cluster_parameters_backup_dest
├── cluster_parameter.20240710T103610.obbak # Information of non-default cluster-level configuration items. File naming format: `cluster_parameter.[timestamp]`
└── cluster_parameter.20241018T140609.obbak

Log archive directory

For backup media such as NFS, OSS, and Azure Blob, the directories created by the log archiving feature at the archive destination and the types of files stored in each directory are as follows:

log_archive_dest
    ├── check_file
    │   └── 1002_connect_file_20230111T193049.obbak // Connectivity check file
    ├── format.obbak                                // Formatted information of the backup path
    ├── rounds                                      // Placeholder directory for Rounds
    │   └── round_d1002r1_start.obarc               // Placeholder for Round start
    ├── pieces                                      // Placeholder directory for Pieces
    │   ├── piece_d1002r1p1_start_20230111T193049.obarc // Placeholder for Piece start, named as piece_DESTID_ROUNDID_PIECEID_start_DATE
    │   └── piece_d1002r1p1_end_20230111T193249.obarc   // Placeholder for Piece end, named as piece_DESTID_ROUNDID_PIECEID_end_DATE
    └── piece_d1002r1p1                             // Piece directory, named as piece_DESTID_ROUNDID_PIECEID
        ├── file_list.0.obarc
        ├── piece_d1002r1p1_20230111T193049_20230111T193249.obarc // Records the continuous interval of the Piece
        ├── checkpoint   
        ├── single_piece_info.obarc                 // Records the metadata of the current Piece
        ├── tenant_archive_piece_infos.obarc        // Records the metadata of all frozen Pieces before the current Piece
        ├── file_info.obarc                         // List of all log stream files
        ├── logstream_1                             // Log stream 1
        └── logstream_1001                          // Log stream 1001

In the above log archive directory, the top-level directory contains the following three types of data:

• format.obbak: records the metadata of the archive path, including information such as the tenant using the path.

• check_file: used for connectivity check of the user log archive directory.

• rounds: a summary list of all Rounds in the log archive, recording the list of all Rounds.

• pieces: a summary list of all Pieces in the log archive, recording the list of all Pieces.

• piece_d1002r1p1: the directory for a Piece in the log archive, named as piece_DESTID_ROUNDID_PIECEID. Here, DESTID refers to the id corresponding to log_archive_dest; ROUNDID refers to the id of the log archive Round, which is a monotonically increasing integer; and PIECEID refers to the piece_id of the log archive Piece, which is also a monotonically increasing integer.

  A log archive Piece directory contains the following data:

  • file_list.0.obarc: this file records the files and directories contained in the current directory.

  • piece_d1002r1p1_20230111T193049_20230111T193249.obarc: this file displays the id, start, and end times of the current Piece and is only for informational purposes.

  • checkpoint: this directory is used by the active Piece to record the archive point. The ObArchiveScheduler module periodically updates the archive point information in this directory.

  • single_piece_info.obarc: this file records the metadata of the current Piece.

  • tenant_archive_piece_infos.obarc: this file records the metadata of all frozen Pieces in the current tenant.

  • file_info.obarc: this file records the list of log stream files within the Piece.

  • logstream_1: this directory records the log files of log stream 1, which is the system log stream of the OceanBase Database tenant.

  • logstream_1001: this directory records the log files of log stream 1001. Log streams with numbers greater than 1000 are the user log streams of the OceanBase Database tenant.

Differences from V3.x/V2.x

Log archiving

Data backup

Physical restore

Partner certifications

For a list of partners that have completed certification with OceanBase Database, see Industrial partners.

On the Industrial partners page, select Data Integration & Backup > Backup & Recovery under Select Solution Type. This will display a list of partners that have completed certification with OceanBase Database, along with the certified versions and the validity periods of the certificates.

References

For more information about physical backup and restore, see Backup and restore.