Hello,
We just installed a HP MSL 4048 (Fiber Channel).

I do not know how to configure amanda.conf because there is several sg
created by the library (it has 4 magazines).

I suppose that :
tapedev "/dev/st0"

But how about :
changerdev
changerfile
tpchanger

In dmesg :

qla2xxx 0000:07:01.0:
 QLogic Fibre Channel HBA Driver: 8.01.07-k1
  QLogic QLA2340 -
  ISP2312: PCI-X (133 MHz) @ 0000:07:01.0 hdma-, host#=0, fw=3.03.20 IPX
  Vendor: HP        Model: HSV200            Rev: 5100
  Type:   RAID                               ANSI SCSI revision: 05
  Vendor: HP        Model: HSV200            Rev: 5100
  Type:   RAID                               ANSI SCSI revision: 05
  Vendor: HP        Model: Ultrium 3-SCSI    Rev: M22W
  Type:   Sequential-Access                  ANSI SCSI revision: 03
  Vendor: HP        Model: MSL G3 Series     Rev: 5.30
  Type:   Medium Changer                     ANSI SCSI revision: 05
scsi 0:0:0:0: Attached scsi generic sg0 type 12
scsi 0:0:1:0: Attached scsi generic sg1 type 12
scsi 0:0:2:0: Attached scsi generic sg2 type 1
scsi 0:0:2:1: Attached scsi generic sg3 type 8
st: Version 20050830, fixed bufsize 32768, s/g segs 256
st 0:0:2:0: Attached scsi tape st0