Hello,
I can see that having separate machines driving different drives within a
single autochanger could significantly improve speed, but Bacula already has
significant difficulties dealing with multiple drives on a single machine, so
this situation is far more complex in terms of communications an locking. At
the moment, I don't really see how to implement this, and in any case with
the current equipment it is impossible because I don't have such an
autochanger.
If you can find a programmer to design and implement this, I would be willing
to discuss it with him/her to determine if it is feasible. I hesitate to add
this to the projects list until we find someone who can design and implement
it.
Certainly in another couple of years this and the project about writing a
single job to multiple drives at the same time will be very interesting
projects, but I suspect that at the moment, unless someone can come up with
some serious programming resources, these are a bit high end for Bacula (at
the moment), especially since there are a number of really critical
functionalities that are missing.
Best regards,
Kern
On Thursday 17 July 2008 18:05:54 Shad L. Lords wrote:
> Item 1: Allow tape drives to be associated with autochanger
> resource on different host
> Origin: Shad Lords <slords at lordsfam dot net>
> Date: 17 July 2008
> Status:
>
> What: Allow tape drives that are part of an autochanger but are
> connected to different hosts to be associated with the robot
> autochanger.
>
> Why: Many large autochangers that have multiple drives recommend
> connecting drives up to different hosts to improve library
> performance. Doing so allows you to utilize full bus
> bandwidth, split pool space, and utilize separate cpus to
> achieve maximum throughput.
>
> Note: A single robot controls multiple drives but is only connected
> to one machine. It is currently possible to work around
> things by having remote hosts issue mtx commands over ssh but
> nothing prevents multiple mtx commands from being issued at
> the same time.
>
> Note: By not being able to associate drives with their autochanger
> you may not be taking full advantage of available drives for
> backup/restore purposes. In a job you can't specify multiple
> libraries/drives, however all the drives on both (multiple)
> hosts have access to all tapes in the library and there isn't
> any reason any one of the drives couldn't be used for
> backup/restore purposes.
>
> Note: Sample config:
>
> host1-sd.conf
> =============
>
> Autochanger {
> Name = ait4-changer
> Device = ait4-drive1
> Device = ait4-drive2
> Device = ait4-drive3
> Device = ait4-drive4
> Changer Command = "/usr/lib/bacula/mtx-changer ..."
> Changer Device = /dev/sg0
> }
>
> Device {
> Name = ait4-drive1
> Archive Device = /dev/nst0
> Drive Index = 0
> Auto Changer = yes
> Media Type = ait4
> ...
> }
>
> Device {
> Name = ait4-drive2
> Archive Device = /dev/nst1
> Drive Index = 1
> Auto Changer = yes
> Media Type = ait4
> ...
> }
>
> host2-sd.conf
> =============
>
> Device {
> Name = ait4-drive3
> Archive Device = /dev/nst0
> Drive Index = 2
> Auto Changer = yes
> Media Type = ait4
> ...
> }
>
> Device {
> Name = ait4-drive4
> Archive Device = /dev/nst1
> Drive Index = 3
> Auto Changer = yes
> Media Type = ait4
> ...
> }
>
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