DMS task running out of memory

Question

Hi, I am trying to migrate my postgresql DB data to s3 in Parquet format .. I have used the below json for my task, I am getting the error  "**Last Error Replication task out of memory. Stop Reason FATAL_ERROR Error Level FATAL**" , machine type: t3.medium  , I have tried reducing the commit rate but got same error .   task json: 
```
{
  "StreamBufferSettings": {
    "StreamBufferCount": 3,
    "CtrlStreamBufferSizeInMB": 5,
    "StreamBufferSizeInMB": 8
  },
  "ErrorBehavior": {
    "FailOnNoTablesCaptured": true,
    "ApplyErrorUpdatePolicy": "LOG_ERROR",
    "FailOnTransactionConsistencyBreached": false,
    "RecoverableErrorThrottlingMax": 1800,
    "DataErrorEscalationPolicy": "SUSPEND_TABLE",
    "ApplyErrorEscalationCount": 0,
    "RecoverableErrorStopRetryAfterThrottlingMax": true,
    "RecoverableErrorThrottling": true,
    "ApplyErrorFailOnTruncationDdl": false,
    "DataTruncationErrorPolicy": "LOG_ERROR",
    "ApplyErrorInsertPolicy": "LOG_ERROR",
    "EventErrorPolicy": "IGNORE",
    "ApplyErrorEscalationPolicy": "LOG_ERROR",
    "RecoverableErrorCount": -1,
    "DataErrorEscalationCount": 0,
    "TableErrorEscalationPolicy": "STOP_TASK",
    "RecoverableErrorInterval": 5,
    "ApplyErrorDeletePolicy": "IGNORE_RECORD",
    "TableErrorEscalationCount": 0,
    "FullLoadIgnoreConflicts": true,
    "DataErrorPolicy": "LOG_ERROR",
    "TableErrorPolicy": "SUSPEND_TABLE"
  },
  "TTSettings": {
    "TTS3Settings": null,
    "TTRecordSettings": null,
    "EnableTT": false
  },
  "FullLoadSettings": {
    "CommitRate": 500,
    "StopTaskCachedChangesApplied": false,
    "StopTaskCachedChangesNotApplied": false,
    "MaxFullLoadSubTasks": 4,
    "TransactionConsistencyTimeout": 600,
    "CreatePkAfterFullLoad": false,
    "TargetTablePrepMode": "DO_NOTHING"
  },
  "TargetMetadata": {
    "ParallelApplyBufferSize": 0,
    "ParallelApplyQueuesPerThread": 0,
    "ParallelApplyThreads": 0,
    "TargetSchema": "",
    "InlineLobMaxSize": 0,
    "ParallelLoadQueuesPerThread": 0,
    "SupportLobs": true,
    "LobChunkSize": 0,
    "TaskRecoveryTableEnabled": false,
    "ParallelLoadThreads": 0,
    "LobMaxSize": 6400,
    "BatchApplyEnabled": false,
    "FullLobMode": false,
    "LimitedSizeLobMode": true,
    "LoadMaxFileSize": 0,
    "ParallelLoadBufferSize": 0
  },
  "BeforeImageSettings": null,
  "ControlTablesSettings": {
    "historyTimeslotInMinutes": 5,
    "HistoryTimeslotInMinutes": 5,
    "StatusTableEnabled": false,
    "SuspendedTablesTableEnabled": false,
    "HistoryTableEnabled": false,
    "ControlSchema": "",
    "FullLoadExceptionTableEnabled": false
  },
  "LoopbackPreventionSettings": null,
  "CharacterSetSettings": null,
  "FailTaskWhenCleanTaskResourceFailed": false,
  "ChangeProcessingTuning": {
    "StatementCacheSize": 50,
    "CommitTimeout": 1,
    "BatchApplyPreserveTransaction": true,
    "BatchApplyTimeoutMin": 1,
    "BatchSplitSize": 0,
    "BatchApplyTimeoutMax": 30,
    "MinTransactionSize": 500,
    "MemoryKeepTime": 600,
    "BatchApplyMemoryLimit": 2048,
    "MemoryLimitTotal": 3500
  },
  "ChangeProcessingDdlHandlingPolicy": {
    "HandleSourceTableDropped": true,
    "HandleSourceTableTruncated": true,
    "HandleSourceTableAltered": true
  },
  "PostProcessingRules": null
} 
```

Accepted Answer

Hi,

If the machine on which you create the replication task is machine of type: t3.medium, try to go with a bigger machine (.large, .xlarge, etc.) They will have more memory and you task will succeed when you find the type that is big enough.

If it's a 1-shot exercise, go directly to a very big instance: it will save you time, hence money.

If this task executor will last, you may want to optimize its size to the smallest possible one to remain as frugal as possible.

Best,

Didier

Answer

The t3.medium instance type has 4GB of memory
MemoryLimitTotal is set 3500 which closure to 4GB. You can adjust this to lower value.
Please check the CloudWatch metrics metrics and logs of the DMS instance for further information on how the resources are being used.
If required you may need to upscale the DMS instance.
[https://repost.aws/knowledge-center/dms-troubleshoot-errors]() is trobleshooting guide.

DMS task running out of memory

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