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[Duplicity-talk] Re: Preventing access time modification?
From: |
Axel Beckert |
Subject: |
[Duplicity-talk] Re: Preventing access time modification? |
Date: |
Tue, 12 Jun 2007 20:17:30 +0200 |
User-agent: |
Mutt/1.5.9i |
Hi Sam,
On Tue, Jun 12, 2007 at 04:32:44PM +0100, Sam Morris wrote:
> [Sent with private mail because my posts to the ML aren't getting
> through for some reason]
So I (nearly) fullquote back to the list. :-)
[How to avoid modifiying the access time]
> The 'open' system call can accept the O_NOATIME flag.
I already heard about embedded systems which don't use access time at
all, but I didn't know that you just need a flag to open(2).
> From glibc's docs:
> -- Macro: int O_NOATIME
> If this bit is set, `read' will not update the access
> time of the file. *Note File Times::. This is used by
> programs that do backups, so that backing a file up
> does not count as reading it. Only the owner of the
> file or the superuser may use this bit.
Isn't that exactly what duplicity needs? :-)
> and from manpages:
>
> O_NOATIME
> (Since Linux 2.6.8)
Ok, that explains why I haven't heard about it yet. The feature is not
that old. Funny, somehow.
> Do not update the file last access time (st_atime in
> the inode) when the file is read(2). This flag is
> intended for use by indexing or backup programs,
> where its use can significantly reduce the amount of
> disk activity. This flag may not be effective on all
> filesystems. One example is NFS, where the server
> maintains the access time.
>
> so whether you must be the file owner (or root) to use it may be
> dependant on the operating system in question.
And I wonder if it works on elder glibc respectively since when glibc
supports this feature.
> IMO duplicity should have an option that turns this on by default
> for the whole backup.
Full Ack! That's much easier than my conception of setting it back. An
much more performant. Even more performant than the current way. :-)
Thanks for your advice!
Regards, Axel
--
Axel Beckert - address@hidden, address@hidden - http://noone.org/abe/
- [Duplicity-talk] Re: Preventing access time modification?,
Axel Beckert <=