Oplog is an important component in MongoDB used to log the operations in the database. The oplog capacity should be at least 10% of the node capacity, as the oplog records all database operations, including insertions, updates, and deletions. If the oplog capacity is too small, the oplog may be overwritten, affecting the rollback feature of MongoDB. When you purchase an instance, the oplog capacity is 10% of the instance capacity by default and can be expanded to 90% of the instance capacity as needed; however, it cannot be shrunk currently.
2. In the MongoDB drop-down list on the left sidebar, select Replica Set Instance or Shard Instance. The directions for the two types of instances are similar.
3. Above the Instance List on the right, select the region.
4. In the instance list, find the target instance.
5. In the Oplog Info column, click View/Adjust.
6. In the Adjust Oplog pop-up window, confirm the instance information and evaluate the target oplog capacity based on the current capacity.
Note:
The Oplog capacity should be at least 10% of the node capacity. When the size of the Oplog file reaches its maximum capacity, MongoDB starts overwriting previous operation records from the beginning of the file. If the Oplog is too small, it can lead to rapid data overwrite, posing Ops risks.
Interface Parameters
Description
Oplog retention duration
The time it takes for the Oplog storage to be filled. If the Oplog is not full, the retention duration is an estimate.
Current total capacity
The storage capacity of the Oplog for each Mongod node.
Capacity After Scale-out
Use the slider to set the Oplog capacity after scale-out.
7. Click OK, and then in the left sidebar, choose Task Management. Wait for the task to complete the scale-out.
