Re: Amtapetype wrongly reporting compression?

[Gene Heskett]

On Friday 12 January 2018 15:20:51 Luc Lalonde wrote:

> Hello Gene,
>
> Would a variant like this:
>
>      /usr/sbin/mtx load 1 0;
>      /usr/bin/mt -f /dev/st0 compression 0;
>      /usr/bin/mt -f /dev/st0 setblk 524288;
>      /usr/bin/dd if=/dev/zero of=/dev/st0 bs=512k count=1;
>      su amandabackup -c "/usr/sbin/amlabel -f Monthly-LTO7
> 000321L7 slot 1";
>      /usr/sbin/mtx unload 1 0;
>
> work?
>
> During my tests with this, the hardware compression stays disabled
> when I load a new tape.
>
> Thanks!
>
Hey, if it works, its right. ;-)

> On 2018-01-11 10:51 PM, Gene Heskett wrote:
> > 1. rewind the tape.
> > 1a. Do NOT remove tape from drive, or cause it to read the tape
> > other than what I write here until after step 5.
> > 2. read the label out to a 32k file.
> > 3. rewind the tape.
> > 4. Turn the compression off, probably with mt.
> > 5. Immediately re-write that label while the tape is rewound, and
> > the hidden tape id block in front of the label will get rewritten
> > too, with that compression flag off.


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Amtapetype wrongly reporting compression?

[Jon LaBadie]

On Fri, Jan 12, 2018 at 03:20:51PM -0500, Luc Lalonde wrote:
> Hello Gene,
> 
> Would a variant like this:
> 
>     /usr/sbin/mtx load 1 0;
>     /usr/bin/mt -f /dev/st0 compression 0;
>     /usr/bin/mt -f /dev/st0 setblk 524288;
>     /usr/bin/dd if=/dev/zero of=/dev/st0 bs=512k count=1;
>     su amandabackup -c "/usr/sbin/amlabel -f Monthly-LTO7 000321L7 slot
> 1";
>     /usr/sbin/mtx unload 1 0;
> 
> work?
> 
> During my tests with this, the hardware compression stays disabled when I
> load a new tape.
> 
The critical event is whether it remains disabled after the
amanda program opens the tape drive for reading (or R/W).
All amanda programs that deal with the tape drive do a read
of the tape header before doing anything else.

> Thanks!
> 
> 
> On 2018-01-11 10:51 PM, Gene Heskett wrote:
> > 1. rewind the tape.
> > 1a. Do NOT remove tape from drive, or cause it to read the tape other
> > than what I write here until after step 5.
> > 2. read the label out to a 32k file.
> > 3. rewind the tape.
> > 4. Turn the compression off, probably with mt.
> > 5. Immediately re-write that label while the tape is rewound, and the
> > hidden tape id block in front of the label will get rewritten too, with
> > that compression flag off.
> 
> -- 
> Luc Lalonde, analyste
> -
> Département de génie informatique:
> École polytechnique de MTL
> (514) 340-4711 x5049
> luc.lalo...@polymtl.ca
> -
>>> End of included message <<<

-- 
Jon H. LaBadie j...@jgcomp.com
 11226 South Shore Rd.  (703) 787-0688 (H)
 Reston, VA  20190  (703) 935-6720 (C)

Re: Amtapetype wrongly reporting compression?

[Luc Lalonde]

Hello Gene,

Would a variant like this:

    /usr/sbin/mtx load 1 0;
    /usr/bin/mt -f /dev/st0 compression 0;
    /usr/bin/mt -f /dev/st0 setblk 524288;
    /usr/bin/dd if=/dev/zero of=/dev/st0 bs=512k count=1;
    su amandabackup -c "/usr/sbin/amlabel -f Monthly-LTO7 000321L7 
slot 1";

    /usr/sbin/mtx unload 1 0;

work?

During my tests with this, the hardware compression stays disabled when 
I load a new tape.


Thanks!


On 2018-01-11 10:51 PM, Gene Heskett wrote:

1. rewind the tape.
1a. Do NOT remove tape from drive, or cause it to read the tape other
than what I write here until after step 5.
2. read the label out to a 32k file.
3. rewind the tape.
4. Turn the compression off, probably with mt.
5. Immediately re-write that label while the tape is rewound, and the
hidden tape id block in front of the label will get rewritten too, with
that compression flag off.


--
Luc Lalonde, analyste
-
Département de génie informatique:
École polytechnique de MTL
(514) 340-4711 x5049
luc.lalo...@polymtl.ca
-