Risks of backing up live mounted filesystems using dump(8)

[Russell Miller]

On Monday 01 March 2010 08:33:20 pm Jeffrey Metcalf wrote:
> > If you put the filesystem of interest on its own partition, then
> > ISTM you can mount -o remount,ro that one file system, and it should
> > remain static during the backup. All data will still be available,
> > though unmodifiable. Clearly, one would need to do something like
> > an lsof to ensure that nobody is using it when the remount takes
> > place.
> > 
> > Mike
> 
> Thanks Mike.  Could be useful for my needs.  Just curious.  Would such a
> mount -o remount,ro flush any dirty filesystem buffers like sync, or would
> it discard them.
> 
In my experience, a remount can be done on a running system, so I imagine that 
loss of data isn't something designed into that particular operation.

I've done it successfully on each server in a running cluster of about 50 when 
I wanted to set it to noatime.

--Russell