> -----Original Message----- > From: Otto Moerbeek [mailto:[EMAIL PROTECTED] > > On Wed, 15 Aug 2007, Edwards, David (JTS) wrote: > > > Hi, > > > > Tape drives with a very large capacity are very expensive > so I thought I'd use external USB drives instead. [snip]
> I'd say it's not safe, because a /dev/sdXc device will not do proper > EOT detection. Ok. I guess it was too good to be true. > So why jump through all these loops? Just dump to a file on a > filesystem, and you can use filenames to identify backups. You can > also do dump multiple filesystems on a single disk then. A couple of reasons. Firstly, there's no need to prepare the disk, you just take it out of the wrapper and plug the USB cable in. Secondly, it tickled my fancy that two very different block devices could be treated in such a similar way :-) And we wouldn't have to change the backup scripts, just the way we determine which device to use.. There's also the obscurity factor, the data is rather sensitive and it's not likely anyone picking up a disk lost during transport offsite would ever figure out how to retrieve data from it. Disks found on the ground are a lot easier to play with than tapes. On the other hand, the data is encrypted so I really don't have to worry about it too much. > And if yor machine gets fried, it will be possible to identify the > backup files correctly on another machine. This is a similar problem to our past practice of using tapes of course. And tapes are worse in that you have to have the right tape drive to read them as well. It was just a thought. EOT detection is not a problem as we stage the backup and can make sure the set will fit on the disk. On the whole, I think you're probably right though. There are probably lots of other risks neither of us have thought of as well. I haven't tried pulling the plug during a backup yet for instance :-) Of course, that still leaves me with the other problem. I still need to identify a disk which is plugged into a certain (physically labelled) cable so I can mount it. Anyone help with that one? I'm currently grepping through dmesg output at the moment. Can anyone point me towards an API/library I can play with that might let me write something that can link a physical usb-hub/port device to a disk device plugged into it? ciao dave
