Did you look at FSEditLog.EditLogFileOutputStream.flushAndSync()?
This code was re-organized sometime back. But the guarantees it provides
should be exactly same as before. Please let us know otherwise.
Raghu.
Jason Venner wrote:
I have always assumed (which is clearly my error) that edit log writes
were flushed to storage to ensure that the edit log was consistent
during machine crash recovery.
I have been working through FSEditLog.java and I don't see any calls of
force(true) on the file channel or sync on the file descriptor, and the
edit log is not opened with an 's' or 'd' ie: the open flags are "rw"
and not "rws" or "rwd".
The only thing I see in the code, is that the space in the file where
the updates will be written is preallocated.
Have I missed the mechanism that the edit log data is flushed to the disk?
Is the edit log data not forcibly flushed to the disk, instead reling on
the host operating system to perform the physical writes at a later date?
Thanks -- Jason
