Flashes (Alerts)
Abstract
When asynchronous policy-based replication operates in a mode for low-bandwidth, data on the recovery volumes may be inconsistent until the replication next operates in mode for low-latency.
This issue only affects policy-based replication on 8.7.0 and higher. It does not affect Global Mirror or Global Mirror with Change volumes
Content
Asynchronous policy-based replication will dynamically change between two modes of operation based on the write workload and the available bandwidth between systems to provide the best possible recovery point:
* Low latency mode (also known as journaling mode) aims to maintain a recovery point of less than a few seconds
* Low bandwidth mode (also known as cycling mode) is used when the write workload exceeds the available inter-site bandwidth, and will typically maintain an recovery point of 1 minute or higher.
In 8.7.0 and higher, when the replication is operating in low bandwidth mode there is a possibility that write operations are sent to the DR copy out of order. Therefore the data on the DR copy might be inconsistent.
When the replication automatically switches back to low latency mode, the DR copy will be consistent again.
It is not possible to directly view the current mode of operation, however, a recovery point greater than 1 minute typically indicates that low bandwidth mode is in use.
This issue is resolved under SVAPAR-164838 in 8.7.0.4 and 8.7.3.0. Any inconsistency on the DR copy will be automatically corrected after the update is completed - usually within a few minutes.
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Document Information
Modified date:
15 May 2025
UID
ibm17231617