PolarDB:Download backup files

How it works

Downloading a backup file involves these steps:

1. Verify that your cluster meets the prerequisites.

2. In the PolarDB console or via API, create a download task and choose a download destination (OSS or URL).

3. Wait for the conversion task to complete.

4. Retrieve the backup file from your OSS bucket or generate a download link.

Prerequisites

Before you begin, make sure that:

• Cluster edition: Your cluster is an Enterprise Edition cluster of the Cluster series.

• Region: Your cluster is deployed in one of the supported regions: China (Chengdu), China (Guangzhou), China (Qingdao), China (Beijing), China (Shanghai), China (Zhangjiakou), China (Hangzhou), China (Shenzhen), China (Hong Kong), Malaysia (Kuala Lumpur), Indonesia (Jakarta), Japan (Tokyo), Singapore, US (Silicon Valley), US (Virginia), or Germany (Frankfurt).

  The feature will be available in other regions soon.

• RAM permissions: Your RAM user has permissions to download backup files. See RAM user permissions.

• Encryption: The cluster's backup data is not encrypted. Encrypted clusters do not support backup file download.

• Concurrent tasks: No download task is currently running or has failed for this cluster. Only one download task per cluster is allowed at a time.

Billing

The feature supports two download destinations: URL and OSS. Fees vary by destination.

Failed download tasks are not charged. To monitor your usage, go to the PolarDB console and navigate to Settings and Management > Backup and Restoration > Backup Download List. There you can view the Monthly Backup Compute Data Volume and Monthly Outbound Internet Traffic for your cluster.

Limitations

• Expression indexes, foreign keys, and other structural elements are not exported: Items not supported for export include expression indexes, foreign keys, generated columns, hidden columns, views, functions, stored procedures, system variables, and triggers.

• Spatial data type fields cause task failure: If the data contains fields of these types, the conversion task fails: GEOMETRY, POINT, LINESTRING, POLYGON, MULTIPOINT, MULTILINESTRING, MULTIPOLYGON, GEOMETRYCOLLECTION.

• System databases are excluded: The following system databases are not included in the export: information_schema, mysql, performance_schema, sys, __recycle_bin__.

• OSS bucket must use Standard storage class: If the bucket uses a different storage class, convert it to Standard before starting a download task.

  Create the OSS bucket manually before starting the task. If you already have a bucket, skip this step.

• Level-2 backup data cannot be downloaded: Only level-1 backup data is supported. Level-2 backup data is not.

• Cold data archiving blocks download: If cold data archiving is enabled for the cluster, backup sets cannot be downloaded.

• Forward slashes in names cause task failure: If any database or table name contains a forward slash (/), the task fails.

Supported table structure elements (for reference): column information, primary key index, non-primary key indexes, unique index, partitioned table information, table engine, and table-level or database-level character sets and collations.

Download backup files using the console

Download backup files using the API

Use the following DBS API operations in sequence:

1. [DescribeDownloadSupport](https://www.alibabacloud.com/help/en/dms/developer-reference/api-dbs-2021-01-01-describedownloadsupport) — Check whether your cluster supports backup file download.

   If the response indicates the feature is not supported, verify that your cluster's edition and region meet the prerequisites.

2. [CreateDownload](https://www.alibabacloud.com/help/en/dms/developer-reference/api-dbs-2021-01-01-createdownload) — Create a backup file download task.

   - Grant DBS the AliyunDBSDefaultRole permission before calling this API. If not yet granted, do so via the console first. - If TargetType is OSS, create the bucket manually beforehand. The bucket must use the Standard storage class. - If TargetType is URL, save the returned TaskId to retrieve the download link later. - A task cannot be cancelled after it starts. - Download tasks incur fees. See Billing.

3. (Optional) [DescribeDownloadTask](https://www.alibabacloud.com/help/en/dms/developer-reference/api-dbs-2021-01-01-describedownloadtask) — View download task information, including task status.

4. Retrieve the backup file:

   • OSS: Data is written directly to your OSS bucket. View it in the corresponding bucket.

   • URL: Call [DescribeDownloadBackupSetStorageInfo](https://www.alibabacloud.com/help/en/dms/developer-reference/api-dbs-2021-01-01-describedownloadbackupsetstorageinfo) to get the download link.

   - The download link is available for three days after the task completes. The link's validity period ranges from 5 minutes to 1 day, with a default of 2 hours. - Tasks expire after three days and their data is automatically deleted. Create a new task if you need the data after expiration. - Save the download link immediately to prevent leakage. - Third-party download tools may generate extra Internet traffic charges. Use wget or curl instead. See Download commands.

FAQ

Appendix

RAM user permissions

Backup file download permissions are managed through Resource Access Management (RAM). Configure them based on your access requirements.

Grant a RAM user permission to download backup files

If a RAM user cannot create or query download tasks, grant them the AliyunDBSFullAccess policy (full access to Data Disaster Recovery). See Manage RAM user permissions.

Deny a RAM user permission to get download links

To allow a RAM user to use backup and recovery features but block access to download links, create a custom permission policy that denies the dbs:DescribeDownloadBackupSetStorageInfo action:

{
    "Version": "1",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": "dbs:DescribeDownloadBackupSetStorageInfo",
            "Resource": "*"
        }
    ]
}

After creating the policy, grant it to the RAM user.

Allow a read-only RAM user to download backup files

RAM users with only AliyunPolardbReadOnlyAccess cannot download backup files. To grant download access, add the AliyunDBSReadOnlyAccess policy. This allows the user to view download links for created backup download tasks.

See Manage RAM user permissions for instructions.

nohup wget -c -t 0 "<backup-file-download-url>" -O <destination-path/filename> > <log-output-path> &

nohup wget -c -t 0 "http://dbs-xxx.aliyuncs.com/xxx.tar.gz?xxx" -O /backup/examplebackup.tar.gz > /tmp/download.log &

nohup curl -C - --retry 10 "<backup-file-download-url>" -o <destination-filename> > <log-output-path> &

nohup curl -C - --retry 10 "http://dbs-xxx.aliyuncs.com/xxx.tar.gz?xxx" -o /backup/examplebackup.tar.gz > /tmp/download.log &