Ariel Weisberg created CASSANDRA-14383:
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             Summary: If fsync fails it's always an issue and continuing 
execution is suspect
                 Key: CASSANDRA-14383
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14383
             Project: Cassandra
          Issue Type: Bug
          Components: Core
            Reporter: Ariel Weisberg
            Assignee: Ariel Weisberg
             Fix For: 4.0.x, 2.1.x, 3.0.x, 3.11.x


We can't catch fsync errors and continue so we shouldn't have code that does 
that in C*. There was a Postgres bug where fsync returned an error and the FS 
lost data, but subsequent fsyncs succeeded.

The [LastErrorException code in 
NativeLibrary.trySync|https://github.com/apache/cassandra/commit/be313935e54be450d9aaabda7965a2f266e922c9#diff-4258621cdf765f0fea6770db5d40038fR307]
 looks a little janky. What's up with that? When would trySync be something we 
would merely try? If try is good enough why do it at all considering try is the 
default behavior of a series of unsynced filesystem operations.

Also when we fsync in FD it's not just fsyncing that file the FS is potentially 
fsyncing other data and the error code we get could be related to that other 
data so we can't safely ignore it. The filesystem could be internally 
inconsistent as well. This happens because the FS journaling may force the FS 
to flush other data as well to preserve the ordering requirements of journaled 
metadata.

If we ignore fsync errors it needs to be for whitelisted reasons such as a bad 
FD.

I know we have FSErrorHandler and it makes sense for reads, but I'm not sold on 
it being the right answer for writes. We don't retry flushing a memtable or 
writing to the commit log to my knowledge. We could go read only and I need to 
check if that is w



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