[CentOS] how to unmount an NFS share when the NFS server is unavailable?

Thu Jan 27 15:48:46 UTC 2011
Les Mikesell <lesmikesell at gmail.com>

On 1/27/2011 7:30 AM, Rudi Ahlers wrote:
>>> BackupPC doesn't intergrate into cPanel.
>> Why does it have to integrate? It runs on a different machine. Can't you make a
>> remote apache authenticate the same way as a cpanel user would to access its web
>> interface?
> Sorry, I should have explained. cPanel is a web based control panel
> which allows end users to control every aspect of their domain (Web,
> stats, mail, files, databases, logs, DNS, etc) including backups.
> It currently backs up everything over FTP, and works fairly well but
> when a user wants to restore a broken website one of our techs needs
> to download the backup from the FTP server, to the cPanel server and
> then restore it on the client's behalf.
> Thus, mounting the NFS share basically added enough storage to the
> cPanel todo the backups "locally", and then the users can restore the
> backups themselves by logging into cPanel. i.e. all the necessary
> security checks are performed automatically.

If you are going this route, the obvious thing would be to make the 
automounter mount the user's copy into his own space when/if he accesses 
it and unmount the rest of the time.

> But, If we use something like backupPC, then each user will need to be
> created on the BackupPC server (which will be a nightmare)

It's not that complicated. You only need an authentication method that 
would set apache's REMOTE_USER which probably already exists on the 
server and wouldn't be hard to copy elsewhere in whatever way it works 
now - or you can run the server locally with nfs-mounted storage.

> and he then
> has to download the backup to his own PC first (some sites are several
> GB's, into the 10's of GB's), which then means the backup will take
> ages to restore.

No, downloading from the browser is an option, but the server can also 
put files back directly over the same transport that was used for the 
backup.  The only issue that might be a problem would be controlling 
where each user could restore to.  Typically each target host has an 
'owner' and access to the web side is limited to the hosts you own - and 
you can map subdirectory targets to look like separate hosts. But when 
you restore, the commands run as the backuppc user which would typically 
have full root ssh access to the whole target host. There's probably 
some way to work around this - maybe using the ftp transport and 
controlling where the logins can go.

Anyway the big advantage of backuppc is that all identical files are 
pooled so you can keep a much longer history on line.

   Les Mikesell
    lesmikesell at gmail.com