What it means by Committed logs

[nitin sharma <ku...@gmail.com>]

Hi Team,

I have couple of questions related to Log commit :

a) What Committed Logs means?
 i understand that Consumer can pick messages when it is committed, i.e.
when message reached to all in-sync replicas.  But it leaves doubt in my
mind.
 does commit means when all replicas have flushed messages to disk ? or
flushed to OS page case ( and OS may still have not pushed to disk yet) or
message has just reached to replica's JVM and consider committed (i
seriously doubt that)

b) if the Commit log means log has been written to disk then when a broker
restarts, does it look for message in OS page cache for messages still not
flushed to disk and updates its Commit log offset and after that only it
checks with Leader node for lag (message lag) ?

Let me know if above questions are not clearly put and needs clarification

Regards,
Nitin Kumar Sharma.