Migration Preparations

This section describes how to prepare for backup and migration. Before using DRS, ensure that you have completed the required preparations.

Preparing for Backup Files

For details, see Migration Overview in Backup Migration.

Configuring Database Restoration Mode

No configuration is required during a full backup restoration.
During full and incremental backup migration, the recovery mode must be set to Full. The procedure is as follows:
Method 1: Log in to the local database center using Microsoft SQL Server Management Studio. Right-click the database to be migrated and choose Properties from the shortcut menu. In the dialog box that is displayed, click Options, and select Full for Recovery mode.
Figure 1 Recovery mode

Method 2: Run the following SQL commands to set the restoration mode:
```
USE master;  
ALTER DATABASE database_name SET RECOVERY FULL;
```

Destination Database Storage Space

The available storage space of the destination database should be at least 1.5 times larger than the total storage space of the database to be restored.

Migration Duration Reference

A complete backup and migration process consists of the following phases:

Figure 2 Migration diagram

**Table 1** Backup migration
Phase	Name	Description
①	Export the backup files.	The time required for generating database backup files depends on the configuration of the source database. You need to estimate the time based on the configuration of the source database.
②	Upload the backup file to an OBS bucket.	OBS does not limit the upload and download speed. If you access OBS through a public network, the upload and download speed is restricted by the public network bandwidth. For example, if the bandwidth of the public network is 10 MB/s and the network is not affected by other factors, the upload rate is 10 MB/s.
③	Download the backup file to the destination RDS for SQL Server through DRS.	Generally, the download speed is 100 MB/s or 300 GB/h.
④	Restore the backup files to the destination database.	Generally, the recovery speed is about 5 GB/min or 300 GB/h.
Total Duration	Total time consumption = phase ① time consumption + phase ② time consumption + phase ③ time consumption + phase ④ time consumption Service downtime = Service suspension -> Last incremental backup -> Uploading to OBS -> Creating a DRS task for restoration

The following uses an example to describe the time required for backing up and migrating data. You can estimate the migration time in advance. The actual time required depends on the network and database configurations on the client. The time listed in the following table is for reference only.

Example

**Table 2** Backup migration example
Phase	Name	Backup File Size (GB)	Time Required (h)
①	Export the backup files.	283	5.5
②	Upload the backup file to an OBS bucket.	283	8.95
③	Download the backup file by through DRS.	283	0.61
④	Restore the backup files to the destination database.	283	2.24
Total Duration			17.3