RFE: using rsync as a backup tool (preserve access time & compres s destination files) ?

tim.conway at philips.com tim.conway at philips.com
Wed Oct 30 18:54:00 EST 2002

It's not up to the application whether atime gets updated.  That's like 
complaining about find making your hard drive light flash.
The only thing rsync could do would be to note the atime before reading 
the file, then falsely set it back to what it was, after reading the file, 
and hope that it wasn't set to something else in the interim... a kludge 
at best. 

Why not mount the filesystem on an alternate mountpoint, noatime or 
readonly?  On AIX, you can just mount the dir wherever.  In sun, and 
apparently Linux, nfs export it, only to localhost, if you like, and mount 
it readonly.  As Chef Tell used to say, "very simple, very easy", and 
legitimate setting of atime can continue unhindered.

Tim Conway 
conway.tim at sphlihp.com reorder name and reverse domain 
303.682.4917 office, 303.921.0301 cell 
Philips Semiconductor - Longmont TC 
1880 Industrial Circle, Suite D 
Longmont, CO 80501 
Available via SameTime Connect within Philips, caesupport2 on AIM 
"There are some who call me.... Tim?" 

Gilles-Eric Descamps <Gilles-Eric.Descamps at SiliconAccess.com>
Sent by: rsync-admin at lists.samba.org
10/29/2002 05:54 PM

        To:     "'rsync at lists.samba.org'" <rsync at lists.samba.org>
        cc:     (bcc: Tim Conway/LMT/SC/PHILIPS)
        Subject:        RFE: using rsync as a backup tool (preserve access time & compres       s 
destination files) ?

I know those questions have been asked before
but that was more than an year ago.
I'm hoping the situation has evolved now.
I'd like to use rsync as a backup tool
to move around some data.
I often have to move hundreds of GB,
and that takes some time. I'd like to use rsync
so that if something happens, I can restart
the migration without loosing what has already been transfered.
But I noticed that every time I use rsync to backup
some data, it "corrupts"/updates the access time of the source file.
All the backup tools I've previously used preserve the access time
(otherwise, you'll loose your access time if you backup everyday).
Gnu tar has a "--atime-preserve".
I use both the access time (last read) & modification time (last write)
to identify which files to remove from the fast file server.
(I've written a tiny perl script to identify which files are "old").
I wish there was an rsync option to preserve access times (sce & dst).
I would also be delighted if there was another option that would
allow to compress/gzip/bzip files on the destination.
I believe that by having almost same filename -> filename.gz,
and having all times (A, C, M) identical, would be sufficient for a match 
Why compressing files ? it's the best trade-off between ease of use
and compression. having no compression at all for old files leads to
waste of space (even on a cheap slow file server).
Compressing everyfile into a big tarfile makes it difficult to browse
a huge archive (I don't know of a "tar shell").
Keeping the directories uncompressed allows for browsing the data easily.
please ?
Thanks in advance,
Gilles-Eric DESCAMPS

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