I have a copy to tape job which copies from disk to tape using Bacula 7.4.0 and PostgreSQL 9.4 on FreeBSD 10.2

Everything is within one SD

Full details at https://gist.github.com/dlangille/2341a6da8f9ee836270c

The job summary:

 Start time:             09-Mar-2016 19:41:54
 End time:               09-Mar-2016 20:51:02
 Elapsed time:           1 hour 9 mins 8 secs
 Priority:               410
 SD Files Written:       1
 SD Bytes Written:       52,897,660,928 (52.89 GB)
 Rate:                   12752.6 KB/s

If I tar the volumes directly to tape, it takes only 16 minutes.

$ time sudo tar -cf /dev/nsa1 IncrAuto-4525 IncrAuto-4320 IncrAuto-4324 IncrAuto-4321 \
> IncrAuto-4055 IncrAuto-4322 IncrAuto-4319 IncrAuto-3969 IncrAuto-3972 \
> IncrAuto-3973 IncrAuto-3971 IncrAuto-4058

real    15m47.508s
user    0m5.844s
sys     1m51.834s

Spooling attributes is trivial:

09-Mar 20:51 crey-sd JobId 232945: Sending spooled attrs to the Director. Despooling 321 bytes ...
09-Mar 20:51 bacula-dir JobId 232944: Bacula bacula-dir 7.4.0 (16Jan16):

I am not sure where to look to figure this out.

Full job output:

09-Mar 19:41 bacula-dir JobId 232944: Warning: FileSet MD5 digest not found.
09-Mar 19:41 bacula-dir JobId 232944: The following 1 JobId was chosen to be copied: 232778
09-Mar 19:41 bacula-dir JobId 232944: Copying using JobId=232778 Job=BackupCatalog.2016-03-08_03.05.16_52
09-Mar 19:41 bacula-dir JobId 232944: Bootstrap records written to /usr/local/bacula/working/bacula-dir.restore.107.bsr
09-Mar 19:41 bacula-dir JobId 232944: Start Copying JobId 232944, Job=CopyToTape-Full-Just-One-tape-01b.2016-03-09_19.41.51_42
09-Mar 19:41 bacula-dir JobId 232944: Using Device "vDrive-0" to read.
09-Mar 19:41 bacula-dir JobId 232945: Using Device "LTO_0" to write.
09-Mar 19:41 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4525" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 19:41 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4525" to file:block 0:1207281748.
09-Mar 19:47 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4525"
09-Mar 19:47 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4320" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 19:47 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4320" to file:block 0:3844390440.
09-Mar 19:49 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4320"
09-Mar 19:49 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4324" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 19:49 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4324" to file:block 0:3867148676.
09-Mar 19:51 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4324"
09-Mar 19:51 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4321" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 19:51 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4321" to file:block 0:214.
09-Mar 19:59 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4321"
09-Mar 19:59 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4055" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 19:59 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4055" to file:block 0:214.
09-Mar 20:06 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4055"
09-Mar 20:06 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4322" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:06 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4322" to file:block 0:214.
09-Mar 20:13 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4322"
09-Mar 20:13 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4319" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:13 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4319" to file:block 0:214.
09-Mar 20:20 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4319"
09-Mar 20:20 crey-sd JobId 232944: Ready to read from volume "IncrAuto-3969" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:20 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-3969" to file:block 0:218.
09-Mar 20:27 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-3969"
09-Mar 20:27 crey-sd JobId 232944: Ready to read from volume "IncrAuto-3972" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:27 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-3972" to file:block 0:218.
09-Mar 20:34 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-3972"
09-Mar 20:34 crey-sd JobId 232944: Ready to read from volume "IncrAuto-3973" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:34 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-3973" to file:block 0:218.
09-Mar 20:40 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-3973"
09-Mar 20:40 crey-sd JobId 232944: Ready to read from volume "IncrAuto-3971" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:40 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-3971" to file:block 0:218.
09-Mar 20:47 crey-sd JobId 232944: End of Volume at file 1 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-3971"
09-Mar 20:47 crey-sd JobId 232944: Ready to read from volume "IncrAuto-4058" on file device "vDrive-0" (/usr/local/bacula/volumes).
09-Mar 20:47 crey-sd JobId 232944: Forward spacing Volume "IncrAuto-4058" to file:block 0:214.
09-Mar 20:50 crey-sd JobId 232944: End of Volume at file 0 on device "vDrive-0" (/usr/local/bacula/volumes), Volume "IncrAuto-4058"
09-Mar 20:50 crey-sd JobId 232944: End of all volumes.
09-Mar 20:50 crey-sd JobId 232944: Elapsed time=01:09:04, Transfer rate=12.76 M Bytes/second
09-Mar 20:50 crey-sd JobId 232945: Elapsed time=01:09:04, Transfer rate=12.76 M Bytes/second
09-Mar 20:51 crey-sd JobId 232945: Sending spooled attrs to the Director. Despooling 321 bytes ...
09-Mar 20:51 bacula-dir JobId 232944: Bacula bacula-dir 7.4.0 (16Jan16):
  Build OS:               amd64-portbld-freebsd10.2 freebsd 10.2-RELEASE-p8
  Prev Backup JobId:      232778
  Prev Backup Job:        BackupCatalog.2016-03-08_03.05.16_52
  New Backup JobId:       232945
  Current JobId:          232944
  Current Job:            CopyToTape-Full-Just-One-tape-01b.2016-03-09_19.41.51_42
  Backup Level:           Full
  Client:                 crey-fd
  FileSet:                "EmptyCopyToTape" 2011-02-20 20:53:31
  Read Pool:              "FullFile" (From Job resource)
  Read Storage:           "CreyFile" (From Pool resource)
  Write Pool:             "FullsLTO4" (From Job resource)
  Write Storage:          "tape01" (From Job resource)
  Catalog:                "MyCatalog" (From Client resource)
  Start time:             09-Mar-2016 19:41:54
  End time:               09-Mar-2016 20:51:02
  Elapsed time:           1 hour 9 mins 8 secs
  Priority:               410
  SD Files Written:       1
  SD Bytes Written:       52,897,660,928 (52.89 GB)
  Rate:                   12752.6 KB/s
  Volume name(s):         000005L4
  Volume Session Id:      264
  Volume Session Time:    1457220166
  Last Volume Bytes:      386,429,912,064 (386.4 GB)
  SD Errors:              0
  SD termination status:  OK
  Termination:            Copying OK

09-Mar 20:51 bacula-dir JobId 232944: Begin pruning Jobs older than 3 years .
09-Mar 20:51 bacula-dir JobId 232944: No Jobs found to prune.
09-Mar 20:51 bacula-dir JobId 232944: Begin pruning Files.
09-Mar 20:51 bacula-dir JobId 232944: No Files found to prune.
09-Mar 20:51 bacula-dir JobId 232944: End auto prune.