So if I have understood correctly
1 .- # mt-f / dev/nst0 WEOF
2 .- # mt-f / dev/nst0 compression 1
3 .- verify that compression is enabled -> tapeinfo-f / dev/sg5
..
Product Type: Tape Drive
Vendor ID: 'HP'
Product ID: "Ultrium 3-SCSI"
Review: 'Q24D'
Attached Changer: No
SerialNumber: 'HU11039DWP'
MinBlock: 1
MaxBlock: 16777215
SCSI ID: 0
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: Not Loaded
Density Code: 0x44
BlockSize: 0
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0x1
DeCompType: 0x1
Block Position: 1

4.-finally, throw the copy to tape through:
# tar - label = "BACKUP $ DATE_INICIO" - verbose - create -
absolute-names - blocking-factor = 128 - file = / dev/nst0 -
files-from "$ LIST">> $ LOG
(where the variables are reported "$..." through a sh script)

I'm running now. As end (4 hours or so) I comment.

Tests to see if it works I'm doing the compression of directly using a
script that copies of the tape using "tar ...". Do not throw the test
from Bacula because copying a much slower rate compared to "tar .." in
tar around 55 MB /sec, in Bacula no more than 11MB/sec .
A silly question ... it is possible that the hardware compression does
not behave like doing the copy to tape using the command "tar"
directly from the OS instead of through the Bacula?

2011/1/14 John Drescher <drescherjm AT gmail DOT com>:
>> # tapeinfo-f / dev/sg5
>> ...
>> DataCompEnabled: yes
>> ...
>
> This means compression is on and is being used.
>
> Although remember if you had compression off and then wrote anything
> to a tape then tried to turn compression on that tape will not be
> compressed because you can not toggle compression on or off after data
> is written to a tape. You can recover with a rewind then weof. Then
> the tape can be switched to use compression. mt -f status with the
> tape loaded should tell you if compression is enabled on the tape.
>
> John
>



-- 
Jose Antonio Rodriguez Martin
CGI, S.A.
Teléfono: 607372465
skype: jarm-cgi
e-mail: jarodriguez AT cgi DOT es
l -- l


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