[Linux] Filesystem mounts

[linux@flux.org]

Quoting Robert Citek <robert.citek@gmail.com>:
>>  I'm confused as to why you can't just unmount and recover any data  
>>  coincidentally
>>  not overwritten and mount it again.
>
> You can't unmount a filesystem if a processes is using it, but you   
> can move it.

This is the crux of the issue. There's a 24/7 database running that  
accesses that mount and we won't have a maintenance window for a  
couple weeks. I remember a Unix method (not specifically Linux) that  
allowed seeing the underlying mount dir.

Moving the filesystem is not an option as several processes write to it.