On Friday 24 October 2003 04:43, Tony wrote:
>Hi,
>
>Good idea. I have done this now. Went and downloaded the manual
>and there are two DIP switches that are relevant. I quote from
>the manual:
>
>-------
>Data Compression (switches 1 and 2)
>
>If switch 1 is ON (default), HW data compression is enabled. If
>switch 1 is OFF, HW data compression is disabled.
>
>If dip switch 2 is ON (default), then SCSI commands can be used
>to enable or disable HW data compression. To prevent HW data
>compression from being enabled or disabled by SCSI commands, set
>DIP switch 2 to OFF
>-------
>
>That all sounds pretty straight forward. I turned dip switches 1
>& 2 OFF so that HW compression is disabled and can't be turned
>on again by the software.
>
>I would hope that if I have physically set these switches, that
>even putting in a tape that was previously written on with
>compression enabled could not over-ride the DIP switch settings.
>
>I have now changed my drive to these settings and removed the
>stuff from /etc/stinit.def.
>
>I try to label a tape and it works fine. I then run an amcheck
>and still receive the same error:
>
>amcheck-server: strange amanda header: "AMANDA: T"
>ERROR: /dev/nst0: not an amanda tape
>
>If I do "dd bs=1k if=/dev/st0 of=stuff" and then look at the
>file "stuff" the first line is:
>AMANDA: TAPESTART DATE X TAPE daily02fri
>
>followed by a ^L char on the next line and then lots of ^@ chars
>(does this matter, or is it just padding ?)

Q: whats the exact length of that file?

It gets zero padded out to whatever the default packet size is set to, 
most default to 512 bytes.  So thats legit.  Can you rewind the tape, 
then re-write that label file back to it with dd using the 
non-rewinding device nst0, and follow that with a multimeg write to 
flush the buffers?  Use "dd if=/dev/zero of=dev/nst0 count=1000000".  
Then rewind it and "dd if=/dev/st0" should spit the freshly written 
label out on screen.  If all that works, it sounds like we're back to 
an amanda problem.  And I'm scratching what little hair I have 
left...

>I have also tried running
>"amtapetype -c -f /dev/nst0" to effectively erase the tape prior
>to amlabel and amcheck, with the same results as above.
>
>I tried amcheck multiple times and again, it appears to be
>succesful about 5% or less of the time (took me 22 tries to get
>one successful).

Wow!  It should be bulletproof.

>suggestions anyone ?

Hummm, this seems to be awfully consistent, dying on the receipt of 
the first 'T' in the word TAPESTART.  You've made that quotation 
several times now.  I wonder if possibly the parity bit setting is 
miss-matched in the scsi configuration of the different card?

While we're on hardware, how about term power?  It should be, for good 
practice, supplied from the card although having it on at the drive 
too wouldn't hurt anything unless the drive is seperately powered.
If you have a multimeter, any idle data line in the cable should have 
a minimum of 2.75 volts on it, less will lead to weird term errors, 
and is the major reason we wind up sacrificing virgins to the scsi 
bus gods from time to time.

You say the drive is about 6 months old?  Any chance the vendor can 
give it a physical?  Maybe something has gone doofy in it.

>regards,
>Tony.
>
> --- Dana Bourgeois <em-lists AT netgods DOT us> wrote:
>> Or you could check for a DIP switch and force compression off.
>>  My Sony DDS4
>> drive can start with compression either on or off and can
>> either be switched
>> under software control or locked in one mode.  I locked
>> compression off so I
>> don't have this hassle.
>>
>>
>> Dana Bourgeois
>
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-- 
Cheers, Gene
AMD K6-III@500mhz 320M
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