Hi Martin,
I've just checked and data compression is enabled as expected:
tapeinfo -f /dev/nst0
Product Type: Tape Drive
Vendor ID: 'QUANTUM '
Product ID: 'ULTRIUM 4 '
Revision: '2210'
Attached Changer API: No
SerialNumber: 'PW1007AMJ50074'
MinBlock: 1
MaxBlock: 16777215
SCSI ID: 0
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: Not Loaded
Density Code: 0x46
BlockSize: 0
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0x1
DeCompType: 0x1
Block Position: 0
Partition 0 Remaining Kbytes: 172811
Partition 0 Size in Kbytes: 853060
ActivePartition: 0
EarlyWarningSize: 0
It required a tape to be inserted indeed.
Thank you for all your help :)
Adam
On 14/02/18 16:00, Martin Simmons wrote:
Ah, OK (mt shows compression on FreeBSD).
You could try tapeinfo (part of the mtx package). I think you need to have a
tape loaded to make it work.
__Martin
On Wed, 14 Feb 2018 14:47:59 +0000, Adam Weremczuk said:
Hi Martin,
This is what I'm getting from the command:
mt -f /dev/nst0 status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x46 (LTO-4).
Soft error count since last status=0
General status bits on (41010000):
BOT ONLINE IM_REP_EN
So compression is not mentioned here, just density code which is
something different.
I looked into "mt compression" and "mt datacompression" commands but
both don't seem to have a view or status mode.
Even when executed without a parameter they enable compression:
https://wiki.zmanda.com/index.php/Hardware_compression
So I'm reluctant to take the risk with our main backup system which I'm
still learning how to use.
Any ideas?
Thanks
Adam
On 09/02/18 18:32, Martin Simmons wrote:
Possibly "mt status" will show whether hardware compression is enabled?
If you are getting close to 1.6TB per LTO-4 tape (according to JobBytes) then
I think hardware compression must be enabled.
The mt command also allows you to control compression (I'm not sure if you can
change it in the middle of writing to a tape though).
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