Object Storage Service (OSS) Replication Time Control (RTC) helps you meet compliance and business requirements for cross-region replication (CRR). For replication tasks that do not involve historical data, RTC takes effect within 15 minutes after it is enabled. For replication tasks involving historical data, RTC takes effect about one hour after the historical data replication is complete. After RTC takes effect, OSS replicates 99.99% of newly written objects within 10 minutes. RTC also provides near real-time monitoring to track key metrics for your replication tasks.
Billing
After you enable RTC, OSS charges you for data replication traffic. For more information, see Cross-region replication RTC fees.
For a specific region pair, if the replication SLA is not met while replication bandwidth and QPS remain within the specified limits, you are eligible for compensation. For more information, see OSS Replication Time Control (RTC) Service Level Agreement.
Limits
Supported regions
Chinese mainland
You can enable RTC for CRR tasks only between the following regions in the Chinese mainland: China (Hangzhou), China (Shanghai), China (Qingdao), China (Beijing), China (Zhangjiakou), and China (Shenzhen).
Regions outside the Chinese mainland
You can enable RTC for CRR tasks only between the US (Silicon Valley) and US (Virginia) regions.
You cannot enable RTC for buckets without a specified region.
Bandwidth limits
Bandwidth limit between two regions
The bandwidth limit between any two regions (a region pair) is 10 Gbps in the Chinese mainland and 2 Gbps outside the Chinese mainland.
Replication bandwidth limit per region
The bandwidth limit is 20 Gbps for any region in the Chinese mainland and 4 Gbps for any region outside the Chinese mainland.
If your business requires higher bandwidth, contact Technical Support to increase the bandwidth limit.
QPS limits
Replication QPS limit between two regions
The QPS limit between any two regions is 10,000 in the Chinese mainland and 5,000 outside the Chinese mainland.
Replication QPS limit per region
The QPS limit is 20,000 for any region in the Chinese mainland and 10,000 for any region outside the Chinese mainland.
ImportantThe preceding limits apply to replication of non-sequential writes. The QPS limit for sequential writes is 2,000. If the request rate is too high, replication latency increases. When you upload a large number of files, we recommend that you avoid using sequential prefixes for filenames. For more information, see OSS performance best practices.
Enable RTC
You can enable RTC for new or existing replication tasks that apply to an entire bucket, a specified prefix, or a tag.
Monitor RTC replication metrics
After you enable RTC, you can click RTC Metric Monitoring to the right of a CRR task in the OSS console to view RTC metrics, like replication latency, amount of data to replicate, and number of operations to replicate.
The following table describes the RTC monitoring metrics.
Metric | Description |
RTC Replication Latency | The maximum replication latency of operations for the specified replication task. This is the recovery point objective (RPO) for the task. For example, if the replication latency is 1 minute, OSS RTC ensures that all data written to the source bucket more than 1 minute ago has been replicated to the destination bucket. In a disaster recovery scenario, you can recover data to a point in time 1 minute ago. |
RTC Amount of Data to Replicate | The total amount of data pending replication to the destination bucket at a specific point in time. For example, if 800 MB of data is written to the source bucket at 08:00 and CRR replicates 600 MB of data from 08:00 to 08:01, the amount of data to replicate is 200 MB at 08:01. |
RTC Number of Operations to Replicate | The total number of operations that are pending replication to the destination bucket at a specific point in time. Example:
At 08:01, the number of operations to replicate is 10. |
RTC Write Bandwidth | The write bandwidth for data in the source bucket pending replication for the specified task. For example, write operations for two prefixes, prefix1 and prefix2, are performed on the source bucket at 08:00. The total bandwidth is 800 Mbps. In this case:
If the replication task is configured to replicate only the data with the prefix1 prefix from the source bucket, the RTC write bandwidth is 200 Mbps. |
RTC Write QPS | The QPS of write, modification, and deletion operations on data pending replication from the source bucket for the specified task. For example, you upload objects, modify object ACLs, and delete objects in the source bucket at 08:00. The QPS for each type of operation is as follows:
If the replication task is configured to replicate only upload and modification operations, and not deletion operations, the RTC write QPS is 15. If the replication task is configured to replicate all operations from the source bucket, the RTC write QPS is 18. Note RTC write operations include:
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