Are logs in the LDF file being removed after a checkpoint? Using the fn_dblog I can get the active portion of the online transaction log of my database.

But after every checkpoint I can only see 2 entries showing the beginning of the checkpoint LOP_BEGIN_CKPT and the end of the checkpoint LOP_END_CKPT.

I'm wondering whether if the previous logs removed after every checkpoint or they are only ignored because the dbi_checkptLSN value that located in the bootpage indicate to the latest LSN?

If it is result of the dbi_checkptLSN am I able to move that indicator, and if yes how?

If not, and if the logs is not removed how can I access the previous logs?
If your database is in simple recovery the log might be truncated after a checkpoint. 

This does not always occur though for reasons discussed in Factors That Can Delay Log Truncation (the most obvious being an open transaction)

To see the inactive portion of the log you can use the undocumented DBCC log command.

DBCC log(0,1) /*First parameter is database id with 0 as current DB*/


or trace flag 2537 in conjunction with sys.fn_dblog

DBCC TRACEON(2537)

SELECT *
FROM sys.fn_dblog(NULL,NULL)


Of course there is no guarantee that the thing you are looking for will be there. It may be overwritten at any moment.