Daniel Carrera wrote:
> Les Mikesell wrote:
>> I suspect that most people using an external disk use more than one and 
>> leave one connected most of the time.
> 
> I can't see myself ever doing that. I don't know why I would ever need 
> two external disks.

The reason for backing things up is that things go wrong.  Things can go 
wrong that destroy everything in the same location.  If you don't have 
at least 2, the backup copy is going to be in the same location as the 
only other copy you have at least part of the time.

>> It would probably exit on such an error anyway, but there is a bigger 
>> issue. You can't just disconnect a disk without unmounting first anyway 
>> - and the disk isn't going to automatically mount in the right place 
>> without some help either.
> 
> On my system the disk always reliably mounts on /media/Daniel. You just 
> need to give the partition a label ("Daniel") which I would do anyways, 
> simply because I like the disk having a memorable name.

But unless you do a custom install, that's not where backuppc is going 
to want it.

> Alternative, an appropriate entry in /etc/fstab using the disk's UUID 
> can also make sure that the disk is always mounted in the correct path.

So, what happens when you have a more robust system of several disks - 
and maybe part of the time you might want to have more than one 
connected at a time for some reason or other?

> Anyways, checking that the backup directory exists seems like a no 
> brainer, even if you don't think specifically of the case of external disks.

External or not, yanking a disk out from under a running application is 
a little drastic.  I'm pretty sure it does check at startup - and in 
recent versions creates any missing directories.

>> Why not run a script to stop the service and 
>> unmount and another to mount where it needs to be and start the service?
> 
> Ubuntu mounts the external disk automatically. I don't have to type 
> "mount". In addition, to unmount, I usually use the GUI (right-click > 
> unmount). It seems like a lot of hassle to fight the auto-mount 
> mechanism for a simple check that IMO BackupPC should do anyways.

umount should not be able to complete if any process has open files or 
its working directory.  You can't do that sort of thing when you run 
server processes.

> If I wrote a backup tool that was supposed to write to a certain 
> directory, I would check that the directory exists even if I didn't 
> think specifically of the case of external disks.

You find out soon enough anyway - and there's not much you can do about 
it either way.

> It's only a 2-3 line change. It doesn't seem like an unreasonable 
> addition to BackupPC...

Maybe not, but it is quite a philosophical change from the environment 
that typical unix server programs expect.  Most people building a backup 
server would probably start with a stable box expected to be up for 
years even if the targets come and go.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com




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