I have two CentOS machines (virtualized) with a mounted NFS share with the following in
<ipaddr>:/mnt/nfsshare /mnt/nfsshare nfs rsize=1024,wsize=1024,timeo=14,intr,cto,relatime 0 0
EnableMMAP Off and
EnableSendfile Off in each Apache's configuration. Another server connected to the NFS will occasionally copy over a CSS file with an updated version (e.g. when someone applies changes from staging). From the shell this update appears to go through (i.e. updated timestamp and
cat shows the correct data).
However, loading the file from the browser or other tools shows the outdated version. Occasionally, I'll see different responses even (the two Apache servers are load-balanced). After a while the change will seem to go through and Apache will return the correct file contents, but it usually takes a minute or two.