ApsaraDB RDS for SQL Server supports sparse backups, offering more flexible policies and minimal backup retention. Compared with regular backups, they allow faster data restores at lower storage costs. Learn how to configure sparse backups below.
Differences between regular and sparse backups
Item | Regular backup | Sparse backup |
Data retention policy | Backup sets are retained based on the specified data retention policy. At least two and up to seven backup sets must be retained every week. For example, a backup set is retained every Monday and Sunday for 365 days. | You can configure backup policies more flexibly and retain the minimum number of backup sets. For example, a backup set is retained every Monday and Sunday for 7 days, and a backup set is retained on the last day of each month for the long term. |
Storage cost | Many regular backup sets are generated, which increases storage costs. | The backup policies can be configured more flexibly. The minimum number of backup sets is retained, which lowers storage costs. |
Prerequisites
When using the RDS backup service for the first time, you will be prompted to authorize the DBS service-linked role (AliyunServiceRoleForDBS). This is a one-time authorization that must be performed by the root Alibaba Cloud account.
Usage notes
After you configure a sparse backup policy, the configuration takes effect in about 10 to 15 minutes.
The backup policy in the first row is always set to Every Week and cannot be deleted. You must specify at least two days for this policy.
If multiple sparse backup policies are scheduled for the same day, the system generates only one backup set and retains it for the longest retention period specified among those policies.
If you delete a sparse backup policy, the backup sets that were generated by the policy are retained for the original retention period.
After you configure a sparse backup policy, the backup for a specified day is skipped if a backup set is not successfully created or dumped within the backup window. In this case, no backup set is retained. This can happen if the backup fails, the instance is locked, or the level-1 backup set is not dumped before it expires.
For example, you configure a policy to back up data on the first day of each month and retain the backup set for 30 days. If the backup fails on December 1, no backup set is retained for that day.
Incremental backup sets cannot be used to restore data independently because they depend on the corresponding full backup sets. Therefore, if a full backup set that was created before you enabled sparse backup (that is, before you switched to advanced backup settings on the Backup Policy tab) expires, the historical incremental backup sets that depend on it cannot be restored neither.
After you enable the sparse backup feature (that is, after you switch to advanced backup settings on the Backup Policy tab), the system converts the most recent incremental backup set into a full backup set. This full backup set is created during the next full backup.
Billing
A free backup storage quota is provided for your RDS instance. If the total size of the backup files for your RDS instance does not exceed the free quota, no backup storage fees are incurred. If the total size exceeds the free quota, you are charged for the excess backup storage. For more information about the free quota and billing, see Backup fee.
Switch to advanced backup policies
To configure sparse backups, you must first switch to the advanced backup policy page. If you have already switched, you can skip this section.
Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.
In the navigation pane on the left, click Backup and Restoration.
On the Backup and Restoration page, click the Backup Strategy tab, and then click Switch to Advanced Backup Policy.
ImportantIf Switch to Advanced Backup Policy is not displayed on the page, submit an application. After your application is approved, refresh the page to continue.
In the dialog box that appears, select I Understand That Switching To The Advanced Backup Policy Is Irreversible, and then click OK.
ImportantThis action upgrades the backup settings page for the instance. You cannot revert to the previous version of the backup settings page.
The Backup Strategy page is displayed as follows. This indicates that the advanced backup settings are enabled. You can then set a sparse backup policy on this page.
Configure a sparse backup policy
Sparse backup lets you manually configure one or more backup policies to retain a minimum number of backup sets.
Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.
In the navigation pane on the left, click Backup and Restoration.
On the Backup and Restoration page, select the Backup Strategy tab, and click the circled number between SQL Server and Level-1 Backup.
In the dialog box that appears, click Add Backup Policy, configure the sparse backup policy, and then click OK.
Backup cycle
Backup time
Retention period
Every Week
Select one or more days of the week.
Set a different retention period for each policy. The retention period ranges from 7 to 7,300 days.
NoteYou can also select Long-term Retention for a policy to retain backup sets for a long term.
Every Month
Select one or more days of the month or Last Day Of Each Month.
Every Year
Select a specific day of the year. For example, you can select January 1 of each year.
NoteFor more information about other parameters, see Back up an ApsaraDB RDS for SQL Server instance and Use the snapshot backup feature.
The backup policy in the first row is always set to Every Week and cannot be deleted. You must specify at least two days for this policy.
Click Save in the lower-left corner of the Backup Strategy tab.
Configuration Example
The following list describes the parameters that are configured in the preceding figure:
①: Back up data daily and retain each backup set for 7 days.
②: Back up data every Monday and retain the backup set for 30 days.
③: Back up data on the first and last day of each month and retain the backup set for 365 days.
④: Back up data on January 1 of each year and retain the backup set for the long term.
What to do next
View backup policies
On the Backup Strategy page, move the pointer over the circled number to view the configured backup policies.
The number in the circle indicates the number of configured backup policies.
Delete a backup policy
On the Level-1 Backup page, click the 
icon to delete a backup policy.
The backup policy in the first row is always set to Every Week and cannot be deleted. You must specify at least two days for this policy.
