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bug#17149: shred - tape data
From: |
Rupert Russell |
Subject: |
bug#17149: shred - tape data |
Date: |
Tue, 1 Apr 2014 12:18:22 +0000 |
Pádraig,
This seems to be getting my task done.
for i in $(seq 1 $NUMTAPES) ; do
mtx -f $LOADER load $i
for j in $(seq 1 $NUMWIPES); do
shred -v -n 1 $TAPE
mt -f $TAPE rewind
done
shred -v -z -n 0 $TAPE
mt -f $TAPE rewind
mtx -f $LOADER unload $i
done
By the way, is there a difference between what these two write to the media?
mt -f $TAPE erase and
shred -z -n 0 $TAPE
Regards
Rupert Russell
OPERATIONS MANAGER
Ilmor Engineering Ltd
Quarry Road, Brixworth, Northamptonshire, NN6 9UB, UK
Direct: +44 (0)1604 799105
Main: +44 (0)1604 799100
Web: www.ilmor.co.uk
-----Original Message-----
From: Pádraig Brady [mailto:address@hidden
Sent: 31 March 2014 18:33
To: Rupert Russell
Cc: address@hidden
Subject: Re: bug#17149: shred - tape data
On 03/31/2014 12:00 PM, Rupert Russell wrote:
> Hi,
>
> shred -v /dev/st0 # where /dev/st0 is the drive in a multi tape carousel.
>
> This starts well with.
> Pass 1/4 (random) 15MiB
> Pass 1/4 (random) 41MiB
> Pass 1/4 (random) 70MiB
> Pass 1/4 (random).....etc
>
> But when the end of a 200GiB tape is reached in pass 1, 'shred' doesn't
> appear to trigger a rewind or maybe wait for the tape to be rewound before
> attempting to overwrite the data.
>
>
> The final messages before and around the error are:-
>
> Pass 1/4 (random) 190GiB/190GiB 100%
>
> Pass 2/4 (random)
>
> Error writing at offset 1288. No space left on device.
>
> (The next line in my script then runs and unloads the tape.)
>
> Is this not rewinding the tape a bug or my mis-use of the 'shred' command?
shred(1) doesn't rewind the tape.
It could issue an MTREW ioctl or something, though I suspect there are all
sorts of ioctls to consider depending on plaftorm.
I also see the `mt erase` command/ioctl which might suffice?
If not then explicitly handling the tape like this might suffice?
for i in $(seq 3); do
mt -f /dev/st0 rewind
shred -n1 /dev/st0
done
thanks,
Pádraig.
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- bug#17149: shred - tape data, (continued)
- bug#17149: shred - tape data, Rupert Russell, 2014/04/04
- bug#17149: shred - tape data, Pádraig Brady, 2014/04/04
- bug#17149: shred - tape data, Rupert Russell, 2014/04/04
- bug#17149: shred - tape data, Pádraig Brady, 2014/04/04
- bug#17149: shred - tape data, Rupert Russell, 2014/04/04
bug#17149: shred - tape data, Rupert Russell, 2014/04/02
bug#17149: shred - tape data,
Rupert Russell <=