We have two DB servers which are part of Always On. Recently we noticed that log backups haven't been running on them for sometime and their .ldf files were growing. We took a log backup and tried to shrink the log file. Not sure if the shrink actually ran, the wizard closed in 2-3 secs and the .ldf file size didn't reduce.
Later that day it has been found that data as far as two years old have been lost in specific tables in that DB. Impacted tables are less than 10, There are around 500 tables in the DB and more than 100 of them involve daily transactions.
Please clarify if the log backup and shrink has any part to play in this? If yes, how could this have been avoided and what else was supposed to be done to keep the .ldf in check?