ApsaraDB RDS:Use the storage compression feature

Feature description

By default, the storage compression feature is disabled. You can enable the feature for your ApsaraDB RDS for MySQL instance based on your business requirements. After you enable the storage compression feature, the storage cost can be reduced by up to 50%. In theory, after you enable the storage compression feature, the amount of data that can be written is up to 2.5 times the amount of data that can be written before you enable the feature. For example, if the storage capacity of your RDS instance is 100 GB, you can write 100 GB of data before you enable the storage compression feature and you can write up to 250 GB of data after you enable the feature. The actual amount of data that can be written varies based on your business requirements.

The storage compression feature is suitable for table data in data storage and files in log storage, such as transaction log files. You can use the storage compression feature to compress a large amount of data to save disk storage and indirectly reduce data storage costs. The data includes the business data generated in daily operations or logs used for recovery and audit.

Enabling the storage compression feature has minimal impact on the instance performance. For more information, see Appendix: Stress testing of the storage compression performance.

Implementation

ApsaraDB RDS for MySQL leverages the intelligent transparent compression disk developed by Alibaba Cloud and the embedded dedicated chip and uses a compression algorithm whose compression level is equivalent to Level 6 of zlib to compress and decompress data in physical disks in real time. The data compression and decompression process is fully transparent and imperceptible to user applications. This prevents compatibility issues. Transparent compression reduces data migration within the disk and effectively reduces the inherent write amplification of the disk. Compared with traditional soft compression, transparent compression is more efficient and reduces the unit price of data storage without significant impacts on performance.

Billing rules

After you enable the storage compression feature, the billing rule for the storage capacity and the free quota on storage are changed.

Prerequisites

The RDS instance meets the following requirements:

• The RDS instance runs MySQL 8.0, MySQL 5.7, or MySQL 5.6.

• The RDS instance runs RDS High-availability Edition or RDS Cluster Edition.

• The RDS instance uses a dedicated instance type.

• The RDS instance uses Premium ESSDs or Premium Local SSDs.

• If the RDS instance uses Premium ESSDs, the storage capacity ranges from 1,000 to 25,000 GB. If the RDS instance uses Premium Local SSDs, the storage capacity ranges from 1,000 to 2,400 GB.

• The RDS instance uses the subscription or pay-as-you-go billing method.

Limits

• The storage compression feature cannot be disabled after the feature is enabled.

• If you enable the storage compression feature for your RDS instance, the following limits are imposed on specification changes:

  • If the RDS instance uses a dedicated instance type, you cannot change the instance type to a general-purpose instance type.

  • If the RDS instance uses the pay-as-you-go to billing method, you cannot change the billing method to serverless.

  • If the RDS instance uses Premium Local SSDs, you cannot change the storage type to cloud disk.

  • You cannot reduce the storage capacity to a value lower than 1,000 GB.

  • If the RDS instance uses cloud disks, you cannot perform elastic upgrades.

• Read-only RDS instances: Before you can enable the storage compression feature for the primary RDS instance, you must enable the feature for the read-only RDS instances. For more information, see Read-only ApsaraDB RDS for MySQL instances. If you enable the storage compression feature for the primary RDS instance, the storage compression feature is automatically enabled for the new read-only RDS instances attached to the primary RDS instance.

• Backup and restoration:

  • The database backup objects refer to the user data before compression.

  • After you enable the storage compression feature, the backup data cannot be compressed. However, you can enable the storage compression feature for RDS instances that are restored from backup files. For more information, see Backup and restoration.

• Recycle bin: If you enable the storage compression feature for the original RDS instance, the storage compression feature is also enabled for the RDS instance that is restored from the recycle bin. For more information, see Use the recycle bin feature.

Enable the storage compression feature

1. Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which your RDS instance resides. Then, find the RDS instance and click the instance ID.

2. In the Configuration Information section of the Basic Information page, click Enable Storage Compression.

   Note

   If the button is not displayed, you must check whether your RDS instance meets the requirements described in Prerequisites.

3. In the Enable Storage Compression dialog box, read and confirm the usage notes and click OK.

4. Click OK to enable the storage compression feature. The status of the RDS instance changes to Upgrading/Downgrading. If Enabled is displayed for the storage compression feature in the Configuration Information section, the storage compression feature is enabled.

FAQ

How do I view the disk space metrics after I enable the storage compression feature?

On the Standard Monitoring tab of the Monitoring and Alerts page of your RDS instance, you can view the MySQL Storage Space Used (MB) Disk Usage (%), and MySQL Physical Storage Space Used (MB) metrics to analyze the storage usage after the storage compression feature is enabled. For more information, see View the monitoring information.

Appendix: Stress testing of the storage compression performance

If you enable the storage compression feature for your RDS instance, the instance performance is not affected. This section compares the instance performance before and after you enable the storage compression feature to check the impacts of storage compression on instance performance.

• Test environment

  • Application server: an Alibaba Cloud Elastic Compute Service (ECS) instance

  • RDS instance specifications: RDS High-availability Edition and a dedicated instance type that provides 8 cores and 32 GB of memory

  • Storage type: Premium ESSD with I/O performance burst enabled

  • Storage capacity: 1,000 GB

• Test case

  sysbench provides the following test cases:

  • oltp_read_only

  • oltp_read_write

  • oltp_write_only

  Sample command:

  sysbench oltp_write_only --mysql-host=xxxxxx --mysql-port=xxxxxx --mysql-user=xxxxxx --mysql-password=xxxxxx --tables=12 --table_size=4000000 --report-interval=1 --mysql-db=xxxxxx --rand-type=uniform  --threads=1 --time=100 run

• Test results

  • The following figure shows the results of the test on a dataset of 12 GB.

    

    Concurrency	oltp_read_only			oltp_read_write			oltp_write_only
    	Before compression	After compression	Increase ratio	Before compression	After compression	Increase ratio	Before compression	After compression	Increase ratio
    1	6738.05	6534.69	-3%	4698.92	4620.96	-2%	3296.62	3151.49	-4%
    8	49446.32	48834.86	-1%	30464.41	29389.79	-4%	17935.94	17371.47	-3%
    16	79411.76	78639.35	-1%	47852.25	46415.14	-3%	27851.15	27257.97	-2%
    32	100070.48	100314.49	0%	68408.67	68521.4	0%	40468.31	39921.37	-1%
    64	113637.5	112402.16	-1%	82387.07	82751.29	0%	57843.89	57267.82	-1%
    128	113871.22	112133.53	-2%	90124.61	89783.53	0%	69850.39	68477.59	-2%
    256	108770.33	107001.19	-2%	88390.16	88001.18	0%	79330.67	79290.03	0%
    512	104325.11	102797.59	-1%	85701.04	84782.41	-1%	77186.74	76983.98	0%

  • The following figure shows the results of the test on a dataset of 48 GB.

    Concurrency	oltp_read_only			oltp_read_write			oltp_write_only
    	Before compression	After compression	Increase ratio	Before compression	After compression	Increase ratio	Before compression	After compression	Increase ratio
    1	1945.09	1902.89	-2%	1700.04	1748.47	3%	1639.68	1722.17	5%
    8	15934.45	15155.32	-5%	13049.89	13230.25	1%	12203.44	12518.78	3%
    16	32436.32	31072.3	-4%	23130.89	23727.46	3%	20668.33	21196.57	3%
    32	56018.88	55409.98	-1%	38182.38	39864.06	4%	30498.33	31356.85	3%
    64	72838.53	73459.99	1%	51153.83	51888.1	1%	41560.41	42073.77	1%
    128	80598.87	80788.34	0%	58943.65	58837.55	0%	50755.55	51526.62	2%
    256	80500.57	80369.96	0%	58969.94	59222.25	0%	56874.2	56512.52	-1%
    512	74476.62	74758.1	0%	58756.28	58347.02	-1%	58009.1	58565.04	1%

References

• Billable items

• Change instance specifications

• Backup and restoration