Unix/Linux backup account that does not update LAST ACCESS files metadata

Question

I'm actually wondering if on Unix/Linux systems, there is a equivalent of "Backup Operators" on Windows.

On Windows, being member of this group allows to open files without updating their LAST ACCESS metadata.

Is there anything similar on Unix/Linux ?

I know that remounting the whole volume using "noatime" option can give this ability, but this is a non-sense as this would require no one accessing datas at time of backup.

Here is the context of the question :

• The Unix/Linux server is hosting CIFS shares and is a production server accessed by other systems/services.
• A Windows server connecting to the Unix/Linux one thru CIFS shared will open files to backup/search in their content.
• The goal is to avoid update LAST ACCESS metadata on opened files because there might be an archiving solution that would rehydrate files and/or consider files as being updated.

Can someone please help on this subject ?

Thanks

Answer 1

There isn't an equivalent of the "Backup Operators" functionality, and as far as I'm aware there is no easy per-file or per-user method of avoiding setting atime on file access.

Most extN filesystems are mounted with relatime rather than noatime, so access time is updated for reading at most once per (24 hour) period.

Personally, I backup either using a snapshot or by working from modification time (mtime). The snapshot approach might work well for you unless you rely on atime to determine whether or not to include a file in a backup set. If that's what you're doing then you would need to use mtime instead of atime. (Why would you want to include/exclude files based on whether or not they'd been accessed? Surely it would be better to include them only if they'd been changed. Am I misunderstanding your requirement?)