About relatime and nodiratime

[David Curtis]

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Alan E. Davis wrote:
> 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
> 
> 
Highly doubtful that these parameters are causing data loss as you
describe it.

Try:

user at ubuntu:/$ find . -name *.pdf

in the root directory, ie. the top directory.

this may take a while.


Dave
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