- What actually is the nomtime mount option:

Inodes have 3 times:
o atime - access time, updated every time the inode is read(file reads)
o mtime - modification time, updated every time the inode is written (file writes)
o ctime - change time, updated every time the inose contents is changed (but not when the change is just an atime update), e.g.chmod and file modifications will both change ctime.  

o atime updates are always async and they do not go through the intent-log, so can be lost in the event of a system crash
o the noatime mount option disables all atime updates for files in the mounted file system.

o mtime updates always go through the intent log, they can be sync or async depending upon O_SYNC flag and mounting with -o log or delaylog
o the nomtime mount optionis *only* applicable to CFS
o the nomtime mount option does *not* disable mtime updates, instead it performs a *lazy* mtime update - so the mtime is still updated, just delayed a little
o this helps CFS because mtime updates do go through the intent-log (consider a write to a file that does not allocated space).

In summary:
? noatime and nomtime have completely different logic.
? For CFS customers we often suggest noatime and nomtime. For local mount nomtime is not applicable anyway.

- Note that the mtime is not actually updated in the inode on a read operation!