On 11/9/2014 6:53 AM, Kern Sibbald wrote:
> On 11/08/2014 07:35 PM, Dmitri Maziuk wrote:
>> On 11/8/2014 5:36 AM, Kern Sibbald wrote:
>>
>> 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).
>> I notice now, thanks.
>>
>> CommunityDiskBackup.pdf has the same old problem in 2.1 Grouping
>> Storage Devices: as usual, it talks multiple devices and shows 2
>> Device definitions with Archive Device = /disk in both. Personally I
>> don't know how to mount multiple physical devices in the same /disk at
>> the same time and keep them separate too.
> Bacula can only mount one device in any given Device section at a time,
> but in an Autochanger (virtual or not) there are multiple Devices and
> each can have its own directory.  However, if you use different
> directories, you must use different Media Types otherwise, Bacula will
> not know the right directory to look in for "fixed" disks.
>
>> Same goes for 2.2 Virtual Autochanger: it doesn't let you write to
>> multiple (disk) devices, it lets bacula treat a single Archive Device
>> as "multipe devices" -- presumably for concurrent access.
> I am not sure why you believe the above.  Each Device can have a
> different Archive Device path.  The examples probably use the same
> directory so that it does not get too complicated (with Media Types and
> all).  I suggest you just try using different disk devices and see what
> happens.

I do not see how that is possible. It makes sense that each of the 
virtual autochanger's Devices use a different Media Type, since that 
forces volumes to only be "loadable" on the Device in which they exist. 
What makes no sense to me is how that is defined in the Director config. 
The Media Type directive in the Storage resource in bacula-dir.conf is 
required, and as far as I can tell is limited to a single Media Type. If 
a single Storage resource in the Director cannot utilize multiple Media 
Types, then I do not see how a SD virtual autochanger using Devices with 
different Media Types is addressable as a single Storage resource in Dir.

In my testing, I used the below config. Note that I  specified a 
comma-delimited list of the media types in the Media Type directive of 
the Storage resource in bacula-dir.conf (Media Type = disk0,disk1). Dir 
and SD start and run normally, accepting the syntax. Jobs run without 
errors, but only ever utilize the Device with Media Type = disk0, first 
media type listed. If I attempt to run two concurrent jobs, then they 
run sequentially, with one waiting on storage until the other completes. 
No job can use any volume that is not Media Type "disk0". If I switch 
the order of the media types listed in the Media Type directive to Media 
Type = disk1,disk0, then all jobs will write to the Device with Media 
Type "disk1" and never any volumes with media type disk0.

This leads me to believe that while the SD has no problem with a virtual 
autochanger that has Devices with different Media Types, it isn't 
possible to define a single Storage resource in Dir that can utilize it.

# bacula-sd.conf
Autochanger {
   Name = changer1
   Changer Device = /dev/null
   Changer Command = /dev/null
   Device = changer1-0,changer1-1
}
Device {
   Name = changer1-0
   Drive Index = 0
   Autochanger = yes
   Archive Device = /mnt/disk0
   Media Type = disk0
   Automatic Mount = yes
   Always Open = yes
   Label Media = yes
}
Device {
   Name = changer1-1
   Drive Index = 1
   Autochanger = yes
   Archive Device = /mnt/disk1
   Media Type = disk1
   Automatic Mount = yes
   Always Open = yes
   Label Media = yes
}
# eof

# bacula-dir.conf
...
Storage {
   Name = changer
   Address = 192.168.2.9
   SDPort = 9103
   Password = "whatever"
   Device = changer1
   Media Type = disk0,disk1
   Autochanger = yes;
   Maximum Concurrent Jobs = 20
}
...
#eof



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