On 11/07/2014 04:48 PM, Dmitri Maziuk wrote:
> On 11/7/2014 7:10 AM, Kern Sibbald wrote:
>> Hello,
>>
>> I am not sure, but it sounds like you are proposing that Bacula use a
>> raw device for storing a Volume.  This is possible. There might be a
>> trivial advantage in terms of performance, but there is no real
>> advantage or demand to do it.
>
> The advantage is you can pull the disk out and stick a new one in,
> just like you do with the tape.
>
> ...  It is, in general, far better to store
>> Volumes in a filesystem rather than on a raw disk for a number of
>> reasons.  It would even be preferable to dedicate a disk to Bacula and
>> have a filesystem on it such as XFS rather than use it as a raw device.
>
> I agree, however, in the current implementation volumes are files that
> must reside in a single filesystem (or you need a fake autochanger).
> If volumes were directories (i.e. mountpoints), we could use multiple
> removable disks, pull full disk out, stick new one in.
>
>> Maybe you can be more precise about what you want.
>
> Was that clear enough?

I think so.  If I understand correctly, you want disk mount points or
directories to be treated much like a tape drive, so that you can mount
multiple "disks".

I think this feature is already implemented, with one difference from
what I believe you are requesting.  Bacula can already deal with a mount
point where the physical device is removable such as a USB key,
providing your tell Bacula that it is removable.  The difference is that
when the device is mounted, it assumes that it has a filesystem on it
rather than treating it as a raw device.  When the device is first
mounted, Bacula will scan for what volumes are on that device.

Much like the Virtual Autochanger feature, I am not 100% sure where this
is documented, so you may have to search for it. The main requirement
for it to work is to configure the SD Device (even if it is a disk
device) as removable.  I wrote the code to handle backup to USB keys
while I was on vacation -- I just plugged in any USB key, and if there
were any Volumes on the device, they would be used, which is mostly what
you are requesting.

By the way, in case you have not noticed, there are three white papers
posted on the bacula.org web site, two of them, if I am not mistaken,
document Virtual Autochangers as implemented in the community version
(slightly different from the Enterprise version).

www.bacula.org -> Documentation -> White Papers

Best regards,
Kern

>
> Dima
>
>


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