Data Disaster Recovery provides two backup methods: logical backup and physical backup. It also offers multiple backup plan specifications to deliver effective data protection and low-cost backup services for your databases. You can evaluate your business needs to select the backup method and specification that meet your requirements.
Differences between logical and physical backups
Comparison Item | Logical Backup | Physical Backup |
Concept | Database object-level backup. The backup content includes database objects such as tables, indexes, and stored procedures. Common tools include MySQL mysqldump and Oracle exp/imp. | Database file-level backup. The backup content is the database files on the operating system. Common tools include MySQL XtraBackup and Oracle RMAN. |
Full backup principle | DBS splits the data of all tables in a database and executes SQL statements on the database to read the data in multiple threads in parallel. | Installs a backup gateway on the server where the database resides. The backup gateway is then used to back up (copy) the database files. For more information, see Add a backup gateway. |
Incremental backup principle | DBS reads logs stored in the memory of a database and performs incremental backup based on the logs in real time. This prevents an I/O performance drop that may occur when a full backup is performed. The speed at which database logs are read is adjusted based on the rate at which the logs are generated. | |
Features |
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Recommended database size | 1 MB to 1 TB | Larger than 1 TB |
Supported databases |
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Requires backup gateway installation | No | Required |
Backup data size | Because logical backups can selectively back up specific tables or data, they are typically smaller than physical backups. | The size of a physical backup is generally directly related to the actual storage space of the database. It is usually very large because it is a backup of the entire database files. |
How to select a backup plan specification
Data Disaster Recovery offers various backup plan specifications, including serverless, micro, small, medium, large, xlarge, 2xlarge, and 4xlarge. Each specification has a different free data volume quota, billing rate, and backup and recovery performance. Higher-tier specifications provide better performance and a lower unit price.
Specification details
The specifications are as follows:
Backup schedule type | Estimated time required to back up 100 GB of data | Free quota for data backup (GB per month) | Configuration fee for the Chinese mainland | Configuration fee for the China (Hong Kong) region and regions outside China | ||
Configuration fee (USD per month) | Unit price of excess backup data (USD per GB) | Configuration fee (USD per month) | Unit price of excess backup data (USD per GB) | |||
micro | 20 hours | 40 | 5 | 0.117 | 7 | 0.175 |
small | 5 hours | 400 | 22 | 0.055 | 33 | 0.083 |
medium | 2.5 hours | 800 | 35 | 0.039 | 53 | 0.059 |
large | 1.5 hours | 1600 | 56 | 0.024 | 84 | 0.036 |
xlarge | 1 hour | ∞ | 140 | Free of charge | 209 | Free of charge |
If the databases and tables that you want to back up involve issues such as unreasonable table schemas, large tables, or large fields, and you select a backup schedule of relatively low specifications, the resources of the backup schedule may be insufficient to back up the databases or tables and backup exceptions may occur.
In this case, we recommend that you select a backup schedule type with high specifications when you purchase the backup schedule, or upgrade the backup schedule to a type with higher specifications if an exception occurs, and then try again. If the issue still exists, you can join the DBS DingTalk group (ID 35585947) for technical support.
The fees displayed on the buy page prevail.
Higher specifications offer higher backup and restoration performance at lower unit prices. For more information, see Performance tests on backup and restoration.
You can only upgrade a backup schedule. You cannot downgrade a backup schedule. For more information, see Upgrade a backup schedule.
Each calendar month, you are allocated a free quota for data backup. If you do not use up the free quota within a month, the remaining free quota does not roll over into the next month.
If the total amount of data that you back up during a month exceeds the free quota, the excess data is charged based on the corresponding unit price.
How to select a specification
You can select a backup plan specification based on backup and recovery performance and cost-effectiveness.
High-performance requirements:
If your database instance, such as a database in a production environment, requires a high-performance backup plan to perform backup and restore jobs quickly, you can select the 4xlarge or 2xlarge specification for better backup and recovery performance.
High cost-effectiveness requirements:
If you do not have high requirements for backup and recovery performance (speed) and are more concerned about cost-effectiveness, you can follow these steps to calculate and select the most cost-effective backup plan specification:
Estimate the total backup data volume for the month, including full and incremental backups.
Calculate the cost for different specifications using the billing formula and select the most cost-effective one. The billing formula is as follows:
Subscription (upfront) billing = Base fee for the backup specification + (Actual data volume - Free data volume quota) × Corresponding billing rate
NoteFor more information about the billing rates for each specification, see Specification billing standards.
For example, Company A plans to perform a full backup for a 150-GB database four times each month. The estimated total backup volume in the current month is 600 GB. Company A can purchase a backup schedule of one of the following types. The price is applicable in the Chinese mainland.
Fees for the micro type: USD 5 + (600 GB - 40 GB) × USD 0.117/GB = USD 70.52
Fees for the small type: USD 22 + (600 GB - 400 GB) × USD 0.055/GB = USD 33
Fees for the medium type are USD 35. The actual backup data size is less than the free quota. No additional fees are charged.
NoteIn this example, the small type has the lowest price. However, if you require better backup and restore performance, we recommend that you purchase a type with higher specifications.
The preceding example is for reference only. In actual scenarios, you also need to consider data growth during full backups (for example, the data volume increases by 2% at the next full backup) and the data volume of incremental backups.
When the total monthly backup data volume is greater than 5,207 GB, the xlarge specification is the most cost-effective. This specification has no backup data volume limit and provides the best backup performance.
Performance tests for logical and physical backups
Logical backup and recovery
Test procedure
This test uses an RDS for MySQL test instance. A backup plan (logical backup) is created in Data Disaster Recovery, and full and incremental backup tasks are started. Then, Data Disaster Recovery is used to restore the backup set data to the RDS for MySQL test instance while monitoring the backup and recovery performance.
Test environment
Configuration item | Configuration |
Database type | RDS for MySQL (General-purpose) |
Database memory | 2,400M |
Database CPU | 8-core |
Database IOPS | 1,200 |
Test data
Test data | Description | Sample data |
Database size | The total size of the test database, in GB. | 102 GB |
Total records | The total number of records in all tables of the test database. | 150 million |
Single record size | The average size of a record in the test database, in KB. | 1 KB to 100 KB |
Number of fields | The number of fields (columns) in a record of the test database. | 3 to 22 columns |
Field types | The data types of the fields in a record of the test database, including basic MySQL data types such as int, varchar, and datetime. | Covers basic MySQL data types |
Test Results
Full backup
Specification | RPS (records per second) | MBPS (MB/s) |
large | 42,855.7 | 15.3 |
medium | 33,122.2 | 11.8 |
small | 9,569.3 | 3.4 |
micro | 6,756.2 | 1.9 |
If the source database has many tables, table initialization can take a long time during backup and recovery. Therefore, the number of tables in the source database should not exceed 10,000.
If the source database contains tables without primary keys, tables with string primary keys, or tables with composite primary keys, the backup time will also be longer.
Incremental backup
Specification | MBPS (MB/s) |
large | 46.1 |
medium | 29.8 |
small | 14.9 |
micro | 5.0 |
Full restoration
Specification | RPS (records per second) |
large | 34,190.5 |
medium | 19,740.9 |
small | 9,949.4 |
micro | 4,320.2 |
Incremental restoration
Specification | RPS (records per second) |
large | 35,546.9 |
medium | 21,331.4 |
small | 10,061.5 |
micro | 4,972.1 |
Physical backup and recovery
Test procedure
This test uses a self-managed MySQL test instance. A backup plan (physical backup) is created in Data Disaster Recovery, and a full backup task is started. Then, Data Disaster Recovery is used to restore the backup set data to a specified directory (physical recovery involves restoring the database files) while monitoring the backup and recovery performance.
Data Disaster Recovery reads MySQL physical files as a stream and concurrently writes the backup data to cloud storage using multiple streams. Additionally, Data Disaster Recovery supports adjusting the backup concurrency based on the selected specification. Higher-tier specifications provide faster backup speeds. Two compression algorithms are supported: gzip and LZ4. The gzip algorithm provides a higher compression ratio, and the LZ4 algorithm provides a faster backup speed.
Test data
Test data | Description | Example data |
Database size | The total size of the test database, in GB. | 40.3 GB |
Total records | The total number of records in all tables of the test database. | 2 billion |
Number of tables | The number of tables in the test database. | 160 |
Single record size | The average size of a record in the test database, in KB. | 0.2 KB |
Test results
Full backup
Specification and compression format | Time consumed | Backup speed | File size after compression |
small (4 threads) gzip | 636s | 63 MB/s | 21.1 GB |
large (8 threads) gzip | 341s | 118 MB/s | 21.1 GB |
xlarge (16 threads) gzip | 204s | 197 MB/s | 21.1 GB |
small (4 threads) lz4 | 268s | 150 MB/s | 31.1 GB |
large (8 threads) lz4 | 119s | 338 MB/s | 31.1 GB |
xlarge (16 threads) lz4 | 104s | 387 MB/s | 31.1 GB |
Full restoration
Specification and compression format | Data volume after compression | Duration | Recovery speed (relative to raw data size) |
small (4 threads) gzip | 21.1 GB | 320s | 126 MB/s |
large (8 threads) gzip | 21.1 GB | 161s | 250 MB/s |
xlarge (16 threads) gzip | 21.1 GB | 86s | 468 MB/s |
small (4 threads) lz4 | 31.1 GB | 408s | 99 MB/s |
large (8 threads) lz4 | 31.1 GB | 208s | 194 MB/s |
xlarge (16 threads) lz4 | 31.1 GB | 108s | 373 MB/s |