CentOS - Feb 2022 - Any downside to mount -o noatime?

On Thu, Feb 10, 2022 at 06:22:55PM -0800, Kenneth Porter
wrote:
>--On Thursday, February 10, 2022 8:49 PM -0500 Jon LaBadie <jcu at
labadie.us>
>wrote:
>
>> atime updates that occur when {m,c}time are updated add
>> no additional burden.
>
>Understood. If that's the only time it happened, I would be happy with
that.
>
>> So you are concerned about a single "possible" inode update
>> once a day?
>
>I'm using BackupPC to do rsync-based backups of all my systems. The
>"incremental" backups look only at size and timestamp changes. The
>less-frequent "full" backups checksum all my files. That means an
extra
>write for every file that gets checked.
>
>I'd love to have a version of relatime that only did the first kind of
>update, when ctime or mtime changed but not when 24 hours had passed.
 From an earlier post:

   "According to the man page for mount, relatime updates atime
    whenever mtime or ctime are updated, or if neither has been
    updated in the last 24 hours."

Are you reading that as "atime gets updated every 24 hrs"?  If so you
are missing "if needed".  I.e. if the file's data blocks have been
read.

Checking time-stamps and sizes are not operations that cause atime
updates.  Those are inode operations, not data reads.

-- 
Jon H. LaBadie                  jcu at labadie.us

--On Thursday, February 10, 2022 11:08 PM -0500 Jon LaBadie 
<jcu at labadie.us> wrote:
> Are you reading that as "atime gets updated every 24 hrs"?  If so
you
> are missing "if needed".  I.e. if the file's data blocks have
been read.
>
> Checking time-stamps and sizes are not operations that cause atime
> updates.  Those are inode operations, not data reads.
That I got. I was concerned with the case where rsync does a checksum to 
verify that the file's contents didn't change without changing the 
timestamp.