Peter Jeremy writes:
> On 2000-May-25 19:03:56 +1000, Brian Somers <[EMAIL PROTECTED]> wrote:
> >Of course access timestamps are usually useless anyway as most (?!!)
> >people will back up their system from time to time.... OOPS ! I
> >never realised before now - dump *doesn't* update the access time.
>
> This is because dump bypasses the filesystem (it reads the underlying
> device). Therefore the filesystem doesn't see the access.
>
> Other backup tools (tar, pax, cpio etc) access the files through the
> FS amd therefore alter the access time. Some have the ability to
> reset the access time afterwards - but that updates the change time,
> which is probably worse. This is probably good justification for a
> O_NOTACCESS (ie, this isn't a real access) flag on open(2) to request
> that the access time isn't updated.
I check it in FreeBSD 4.0-R
open do not change atime.
> In general, access time is probably the least important of the
> timestamps. This is reflected in the treatment of access time
> updates - unlike all other inode updates, they are not written
> synchronously (non-softupdates) and don't affect soft-updates
> write-ordering (so atime updates can be lost).
>
> As I see it, the major use of access times would be for a true
> hierarchical storage manager (which transparently migrated un-
> referenced files to a tape-library or similar). It's also good
> for things like deleting `old' files in /tmp.
See ports/18813: new port: misc/deleted
this daemon uses access times
[skip].........
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