On Monday 17 January 2005 07:45, Peter Guhl wrote:
>Hi Paul
>
>On Mon, 2005-01-17 at 12:38, Paul Bijnens wrote:
>> But you can do just the same using dd:
>>
>>     dd if=/dev/random of=/dev/st0 bs=32k
>>
>> and count how many 32Kbyte blocks get on the tape.
>> Expect about 15000000000 / 32768 or about 457763 blocks.
>>
>> Remember, it takes about 2-3 hours to fill a tape.
>>
>> Multiple runs should result in an almost constant number of blocks
>> (plus/minus a few hundred).
>
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
> bs=32k dd: /dev/nrsa0: short write on tape device
>1301+0 records in
>1300+1 records out
>42598476 bytes transferred in 13.372441 secs (3185542 bytes/sec)
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
>bs=32k
>dd: /dev/nrsa0: short write on tape device
>1756+0 records in
>1755+1 records out
>57507912 bytes transferred in 18.072619 secs (3182046 bytes/sec)
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
>bs=32k
>dd: /dev/nrsa0: short write on tape device
>127+0 records in
>126+1 records out
>4128840 bytes transferred in 1.362397 secs (3030570 bytes/sec)
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
>bs=32k
>dd: /dev/nrsa0: short write on tape device
>1935+0 records in
>1934+1 records out
>63373386 bytes transferred in 20.628743 secs (3072092 bytes/sec)
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
>bs=32k
>dd: /dev/nrsa0: short write on tape device
>354+0 records in
>353+1 records out
>11567158 bytes transferred in 3.702742 secs (3123944 bytes/sec)
>root@:/usr/local/etc/amanda/backup> dd if=/dev/urandom of=/dev/nrsa0
>bs=32k
>dd: /dev/nrsa0: short write on tape device
>704+0 records in
>703+1 records out
>23035980 bytes transferred in 7.960560 secs (2893764 bytes/sec)
>
>It was a little bit faster ;-) but I guess that's mainly because
> this drive isn't in a very good shape... at least those rapidly
> changing numbers look a lot like that.
>
>Regards
>   Peter

Is that tape being properly rewound Peter?  Most drives will fully 
rewind a tape before they allow it to be ejected, maybe you should 
eject it and look at it between each pass.

Or is this a case of needing to either fix the terms or sacrific a 
virgin over the scsi bus?  I'd go for the former since the latter are 
a bit hard to find these days. :-)

-- 
Cheers, Gene
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Copyright 2005 by Maurice Eugene Heskett, all rights reserved.