AWS DMS migration Premigration assessment possible bug

Question

So I have:
- source: AWS Lightsail DB MYSQL on version 8.0.35
- target: AWS Aurora MYSQL 3.07.0 (8.0.36)

And one Assesment is constantly failing "Validate if the timeout values are appropriate for a MySQL source or target"

Where on results for it says:
- Net Read Timeout: 30
- Net Write Timeout: 60	
- Wait Timeout: 28800
- Message: "Net read, net write and wait timeouts must be greater than 5 minutes for DMS target database to prevent connection drops while replicating. Please increase the timeouts to at least 300 seconds"

The problem is:
I already have set those first 2 timeout's to 600 on parameters group of target db, and also on both source and target endpoints with:
{"AfterConnectScript": "SET net_read_timeout=600; SET net_write_timeout=600; SET replica_net_timeout=600; SET slave_net_timeout=600;"}

Also tried a couple of other fields like replica_net_timeout and slave_net_timeout, but that too did not solve the issue so I am stuck.

Appreciate any help or insights, thanks!

Also posted on: https://stackoverflow.com/questions/78697913/aws-dms-migration-premigration-assessment-possible-bug-on-validate-if-the-timeo

Ruchir_A · Answer

Hi Lucas,

Please set net_read_timeout, net_write_timeout and wait_timeout to a value greater than 300 seconds in the source and target databases.

To confirm that the values have been set at the database level, please login to the source and target databases using a MySQL client like MySQL Workbench and run the below query to get the values:

```
show variables like 'net_read_timeout'
show variables like 'net_write_timeout'
show variables like 'wait_timeout'
```
If the above values are below 300 seconds, then you need to set the parameters at the database level. For Aurora MySQL, please attached a custom DB cluster parameter group to the cluster, set the parameters in this parameter group and reboot the writer instance.

Once the parameters are set to above 300, please create a new pre-migration assessment report.

Paul_M · Answer

Hi everyone, 
I initially got the error message, then after updating my DB instance and DB Cluster parameter groups for MySQL and Aurora MySQL with the value 3600, the premigration assessment was successful.

Try reboot your DB instances after updating the parameter groups

subhashr · Answer

this should give some guidance 
https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Troubleshooting.html#CHAP_Troubleshooting.MySQL.ConnectionDisconnect

AWS DMS migration Premigration assessment possible bug

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