LSN issue when the task stopped and resumed again

[Naga_vivek]

Hi team,
 
1.when we are stopping  and resuming the job it is going into recoverable error state with the below errror. Why is that happening offen.
 
2.Does the below lsn mean we are missing some changes when the task stopped?

3.When we stop the job and resume it again after sometime we need to capture the changes right?will they get capture or will it be lost.

4.Even when we are not doing any changes to the database and if we stop the job and resume it again it is erroring out. could you let me know why?

Errors:(occured mostly when we stop and resume our replicate task)

Task '<Taskname>' encountered a recoverable error

Stream component 'st_0_src' terminated
Stream component failed at subtask 0, component st_0_SRC
Error executing source loop

LSN '<LSN Value>' could not be found, neither in the transaction log nor in the backup log

other errors
Stream component 'st_0_src' terminated
Stream component failed at subtask 0, component st_0_src
Error executing source loop
Encountered an unexpeceted error. Aborting...
mssql_execute_log_lsn_peeper(...) failed upon SQLExecute with LSN parameters '<LSN Value>'
 
we have Production deployment this week so could you let us know how we need to resolve it 

Thanks 

Vivek

[aarun_arasu]

Hello @Naga_vivek ,

Thanks for reaching out to Qlik community.

Can you please helps us with more details about the version and endpoints.

Below are some reference article

https://community.qlik.com/t5/Qlik-Replicate/LSN-could-not-be-found-neither-in-the-transaction-log-n...

https://community.qlik.com/t5/Qlik-Replicate/failed-upon-SQLExecute-with-LSN-parameters/td-p/1768486

Its worth checking with DBA on the existence of the LSN which replicate is complaining

Regards

Arun

[SushilKumar]

Hello Team,

Such issue occurs when your transaction logs retention is configured very low.  QR is designed to keep info of Applied and changes need to read from the transaction logs which referred in the logs as Saved State. 

for E.g.  Qlik task was reading change number 4 ) in the transaction Log 2. you stopped the QR task. and resume the task post 2 hours. 

When you resume the task QR task require " change number 4 (LSN) in the transaction Log 2" to start reading or initializing/positing's itself. if Somehow in the configured location " online logs/transaction logs/backup logs" it will not find then it throws error that "could not be found, neither in the transaction log nor in the backup log." 

until unless the missing transaction log is restored you will not start the task via resume. you have to tell QR task read from later timestamp where you have transaction Log available in configured location.

Regards,

Sushil Kumar

[Heinvandenheuvel]

>> Task 'PP_C035p_DATA_EXT_DB_TO_FF_LOB' encountered a recoverable error

>> LSN '<LSN Value>' could not be found, neither in the transaction log nor in the backup log

These messages are exceedingly clear.

This is NOT a Replicate issue/problem/bug but an environmental one.

If your team cannot deal with them, then they are not ready for production deployment.

>> we have Production deployment this week so could you let us know how we need to resolve it 

You should probably postpone and urgently get some Replicate Professional services to review you production (and dev ) configurations and requirements.

Now to put you a little at ease, it is not unlikely that this is 'just' a DEV source DB environment issue. IN DEV environments is is not uncommon to have to deal with restricted resources and DBA's playing fast and loose with db/tlog/server backups. The Tlog backups do not appear to be available (in the right place). In the Production environment one can expect a rigorous, structured handling of Tlog backups with clear retention requirement and you may never see the DEV reported configuration issues.

Hein.