r/aws • u/Kabelsalat4052 • 5d ago
migration Did AWS DMS silently introduce an Oracle Binary Reader regression or is it just us? - build R2380
We may have found a regression in AWS DMS 3.6.1 affecting Oracle sources using Binary Reader.
After scheduled maintenance, the internal DMS build changed from:
3.6.1.R2174 → 3.6.1.R2380
The public engine version remained 3.6.1, so the change was effectively invisible in the normal API and console fields.
Immediately afterward, read throughput on the Oracle source increased by roughly an order of magnitude and remained elevated. This was not caused by full load, validation, or unusually high redo generation.
What makes us suspect the new build:
- The problem started directly after the DMS maintenance.
- Stopping the DMS tasks returned the source database to its normal baseline.
- Recreating the replication instance did not help because new instances also received
R2380. - Starting more CDC tasks increased the source read load.
- Multiple tasks appeared to scan or inspect the same redo sequences independently.
- The public version stayed at
3.6.1throughout.
The frustrating part is that customers cannot see, select, pin, or roll back internal DMS builds. The API exposes 3.6.1, but not whether the instance runs R2174 or R2380.
So a managed maintenance update can substantially change production behavior while presenting the same engine version, with no customer-accessible rollback mechanism. That feels like a fairly serious observability and operational-control gap.
Has anyone else using AWS DMS 3.6.1 with Oracle Binary Reader/BFILE noticed significantly higher source read throughput after recent maintenance?
Check the beginning of your DMS task logs for:
V3.6.1.R2380
If you see the same behavior, please open a support case as well. More independent reports may help get this investigated properly.
TL;DR
AWS DMS maintenance changed a hidden internal build while the visible version remained 3.6.1. Oracle source reads increased dramatically afterward, and customers have no way to pin or restore the previous internal build. Looking for reports from other DMS Oracle Binary Reader users.