About relatime and nodiratime

[Alan E. Davis]

I noticed recently that on at least one of the machines on which I have
Ubuntu 8.04 installed, new options in /etc/fstab---in particular, relatime.
I am inquiring whether there may be any reason to fear loss of data due to
this new option, and also I want to ask about nodirratime.

Google took me to a kernel mailing list discussion about these optoins.  I
understodd that disk performance is vastly enhanced by using relatime as an
option to mount.  Also, nodiratime, and I think also noatime, were
mentioned.  The discussion made the point that especially on journaling file
systems, wirtes to disk are extremely frequent, and that relative would
reduce the number of writes, and could, it was posted, increase disk
performace by up to 40%!  I assume that the Ubuntu developers have done this
with good reason, perhaps this being one reason that Ubuntu is getting high
marks for performance.

So I set up the ext3 partitions with relatime, and also one or two
partitions with nodiratime, in addition to relatime.  I may have blundered
in this.

I lost an entire directory from my main disk drive, a SATA disk.  It's not a
large directory, but I was storing some of my more recent work---a large
number of PDFs scanned with gscan2pdf (which I highly recommend, by the
way).  The first time I lost the directory, I found it entire, in another
directory as a subdir.  It has disappeared from "Places", into which I had
dragged it into the bookmarks list.  So I moved it back to where it had
been.

About three days later, laden with even more files, it disappeared
completely.  I cannot seem to find it, and I do not posses magic strong
enough to raise it from the dead.

Hence I am posting to this list to ask for further information about the
parameters I mentioned.

  -  is there any way that use of these parameters would lead to loss of a
directory?
  -  Any ideas?
  - Would the use of nodiratime have any possible deleterious effects, of
the nature of the one I have described, due to lack of writing to disk
sufficiently?
  -  The power here on my island is really horrible, and I am not careful
enough to clean it up.  We have power outaged several times a week, and I
have been living at a compound where the backup generator power is not up to
standard.  Could these factors lead to the sympom I have described?


Thank you for any suggestions.

Alan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20080621/d6d02e87/attachment.html>