I don&#x27;t think you can count on the file system to actually persist data on disk when you call flush(). Example <a href="http:&#x2F;&#x2F;rhaas.blogspot.it&#x2F;2014&#x2F;03&#x2F;linuxs-fsync-woes-are-getting-some.html?m=1" rel="nofollow">http:&#x2F;&#x2F;rhaas.blogspot.it&#x2F;2014&#x2F;03&#x2F;linuxs-fsync-woes-are-getti...</a>