Confirm hardware compression is working

Hello, list!

Bacula veriosn 5.0.0 for director, SD and FDs running in Linux hosts.

I've been reading the list archive searching for 'hardware compression' posts, because I need to find a way to confirm that the backups are really being compressed. 

Before using `mt' command, I had this: 
# cat  /sys/class/scsi_tape/nst0/default_compression
-1

Then:
# mt -f /dev/nst0 defcompression 1

and then:
# cat  /sys/class/scsi_tape/nst0/default_compression
1


Even before issuing that `mt' command, the Tape Drive reported Compression is enabled (see below).

Here is a volume info:
*list volume=Axxxx
+---------+------------+-----------+---------+-----------------+----------+--------------+---------+------+-----------+-----------+---------------------+
| mediaid | volumename | volstatus | enabled | volbytes        | volfiles | volretention | recycle | slot | inchanger | mediatype | lastwritten         |
+---------+------------+-----------+---------+-----------------+----------+--------------+---------+------+-----------+-----------+---------------------+
|      20 | Axxxx      | Append    |       1 | 603,938,958,336 |      645 |      432,000 |       1 |    5 |         1 | LTO-6     | 2024-10-24 09:02:55 |
+---------+------------+-----------+---------+-----------------+----------+--------------+---------+------+-----------+-----------+---------------------+

Using LTO-6 tapes, can I assume 603,9 gigabytes is stored being (hardware)compressed?



tapeinfo output:
# tapeinfo -f /dev/sg1
Product Type: Tape Drive
Vendor ID: 'IBM     '
Product ID: 'ULT3580-HH6     '
Revision: 'E6R3'
Attached Changer API: No
SerialNumber: '10WT067593'
TapeAlert[10]:    No Removal: Cannot unload, initiator is preventing media removal.
MinBlock: 1
MaxBlock: 8388608
SCSI ID: 0
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: 0x68
Density Code: 0x5a
BlockSize: 0
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0xff
DeCompType: 0xff
Block Position: 1
Partition 0 Remaining Kbytes: -1
Partition 0 Size in Kbytes: -1
ActivePartition: 0
EarlyWarningSize: 0
NumPartitions: 0
MaxPartitions: 3


Regards,
-- 
Gabriel