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Database Migration Service supports the following backup types for homogeneous
SQL Server migrations to Cloud SQL.
Full backups
Full backups are the backbone of the migration process.
They contain all the data in your database at the point in time when you
export them. The full backup file is required for migration.
Differential backups
Differential backups contain all the source data
that appeared in your database since the last full backup file.
Differential backups are useful if you have a lot of data to replicate and
want to handle it in bulk rather than upload multiple transaction log files.
The differential backup file is optional for migration.
Transaction log files
These files contain a list of change operations
that take place in your database. Database Migration Service uses this information
to replicate data updates in your destination database during the
Change Data Capture (CDC) phase.
For homogeneous SQL Server migrations, Database Migration Service
supports only the continuous migration type (for more information see
Continuous migrations data flow). This means that migration
jobs always proceed to the CDC phase, but you don't get errors if you don't
upload any transaction log files. If you don't upload any transaction log
files, you need to promote the migration job when the initial load phase
is over. See
Promote a migration job.
As you prepare the backup files for your migration, make sure you consider
the following:
Naming conventions: Each backup file type needs to use a specific naming
convention. See
Prepare your backup files.
Folder structure: Each backup file type needs to be stored in a separate
folder in the Cloud Storage bucket you use for migration. See
Store backup files in a Cloud Storage bucket.
Encryption: You can use encrypted backups for your migration. If you want
to encrypt the backup files, you need to encrypt all types of backup files
you use for a specific database included in your migration. See
Use encrypted backup files.
Migration job configuration: If you use a differential backup file for any
database included in your migration, you need to configure the migration job
so that Database Migration Service can recognize the differential backup files
in your Cloud Storage bucket. See
Create a migration job
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-25 UTC."],[[["\u003cp\u003eFull backups are mandatory for SQL Server migrations to Cloud SQL, as they contain all the database data at the time of export.\u003c/p\u003e\n"],["\u003cp\u003eDifferential backups, containing data changes since the last full backup, are optional but can be beneficial for managing large amounts of data.\u003c/p\u003e\n"],["\u003cp\u003eTransaction log files, which track database changes, are utilized by the Database Migration Service for continuous data replication (CDC), although not providing them won't cause errors.\u003c/p\u003e\n"],["\u003cp\u003eProper backup file organization, including specific naming conventions and distinct folder structures in Cloud Storage, is required for successful migration.\u003c/p\u003e\n"],["\u003cp\u003eAll backup files for a specific database must be encrypted together if you choose to use encryption.\u003c/p\u003e\n"]]],[],null,["# Supported types of backup files\n\nDatabase Migration Service supports the following backup types for homogeneous\nSQL Server migrations to Cloud SQL.\n\nFull backups\n: Full backups are the backbone of the migration process.\n They contain all the data in your database at the point in time when you\n export them. **The full backup file is required for migration.**\n\nDifferential backups\n: Differential backups contain all the source data\n that appeared in your database since the last full backup file.\n Differential backups are useful if you have a lot of data to replicate and\n want to handle it in bulk rather than upload multiple transaction log files.\n **The differential backup file is optional for migration.**\n\nTransaction log files\n\n: These files contain a list of change operations that take place in your database. Database Migration Service uses this information to replicate data updates in your destination database during the Change Data Capture (CDC) phase. For homogeneous SQL Server migrations, Database Migration Service\n supports only the continuous migration type (for more information see\n [Continuous migrations data flow](/database-migration/docs/sqlserver/scenario-overview#data-flow-migration-types)). This means that migration\n jobs always proceed to the CDC phase, but you don't get errors if you don't\n upload any transaction log files. If you don't upload any transaction log\n files, you need to promote the migration job when the initial load phase\n is over. See\n [Promote a migration job](/database-migration/docs/sqlserver/finalize-migration).\n\nAs you prepare the backup files for your migration, make sure you consider\nthe following:\n\n- Naming conventions: Each backup file type needs to use a specific naming\n convention. See\n [Prepare your backup files](/database-migration/docs/sqlserver/export-backup-files).\n\n- Folder structure: Each backup file type needs to be stored in a separate\n folder in the Cloud Storage bucket you use for migration. See\n [Store backup files in a Cloud Storage bucket](/database-migration/docs/sqlserver/storage-buckets).\n\n- Encryption: You can use encrypted backups for your migration. If you want\n to encrypt the backup files, you need to encrypt all types of backup files\n you use for a specific database included in your migration. See\n [Use encrypted backup files](/database-migration/docs/sqlserver/backup-file-encryption).\n\n- Migration job configuration: If you use a differential backup file for any\n database included in your migration, you need to configure the migration job\n so that Database Migration Service can recognize the differential backup files\n in your Cloud Storage bucket. See\n [Create a migration job](/database-migration/docs/sqlserver/create-migration-job)\n\nWhat's next\n-----------\n\nFor a detailed step-by-step migration guide, see\n[Cloud SQL for SQL Server migration guide](/database-migration/docs/sqlserver/guide)."]]
