RFE: using rsync as a backup tool (preserve access time & com press
destination files) ?
tim.conway at philips.com
tim.conway at philips.com
Fri Nov 15 23:17:00 EST 2002
The way gnutar "preserves" atime is by noting it before the read, and
setting it back after the read, thus wiping out a legitimate setting of
atime occuring during that interval.
Yeah, the netapps mess with unix times. Did you notice that mtime and
ctime always match?
Now that I know you're on a netapp, though, your problems are solved.
Snapshot and sync from the snapshot, then expire the snapshot if your data
is rapidly-changing, so it doesn't hold a bunch of old space.
Also, I just mounted up a netapp readonly (on a system also mounting same
directory readwrite elsewhere). even though it's readonly, the netapp
sees the read and updates atime... however, I still like the snapshot
idea.
Tim Conway
conway.tim at spilihp.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>
11/15/02 03:50 PM
To: Tim Conway/LMT/SC/PHILIPS at AMEC
cc:
Subject: RE: RFE: using rsync as a backup tool (preserve access time & com press
destination files) ?
Classification:
> From: tim.conway at philips.com [mailto:tim.conway at philips.com]
> Sent: Wednesday, October 30, 2002 10:53 AM
>
> 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.
Well, gnu tar provides a "--atime-preserve".
All applications which backup filesystems (legato, quickrestore,
budtools)
preserve times on an application level.
A backup tool is supposed to bypass normal filesystem access
as it's supposed to be transparent.
> 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.
Because that does not work. I just tried it.
The file server is a NetApp box running a proprietary OS (not unix, nor
windows).
mounted the NFS filesystem with noatime & readonly,
but guess what, when you read a file, the box updates the read time
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