On Sunday, Dec 28, 2003, at 22:47 Australia/Sydney, Wojciech Puchar 
wrote:

> that's driver info, not program. i can't use 32K blocks with any 
> program
> including dd

Well, the 32256 maximum below is straight from pax.h - nothing to do 
with
the kernel. dd(1) with 64 KB blocks works fine for me to a DDS2 drive,
under NetBSD 1.6R (unfortunately I don't have a tape drive attached to
my 1.6ZG system):

ksh$ dd if=/dev/zero of=/dev/rst0 bs=64k count=160
160+0 records in
160+0 records out
10485760 bytes transferred in 51.613 secs (203161 bytes/sec)

I assume you have the hardware blocksize set to 0 to force variable
blocksizes? You should see this in the output from "mt status".

>> To: Wojciech Puchar <wojtek@tensor.3miasto.net>
>> Cc: current-users@NetBSD.org
>> Subject: Re: what have changed in st driver?
>>
>>
>> On Sunday, Dec 28, 2003, at 07:11 Australia/Sydney, Wojciech Puchar
>> wrote:
>>
>>> i've been able to use 32K blocks on exactly that tape drive in 1.5.*
>>>
>>> now:
>>>
>>> root@serwer# tar -b64 -cvf /dev/rst0 /bin /sbin
>>> tar: Write block size of 32768 too large, maximum is: 32256
>>
>> I think you'll find this is due to the switch to tar-is-pax. From the
>> pax(1) manpage:
>>
>>       -b blocksize
>>             When writing an archive, block the output at a positive
>> decimal
>>             integer number of bytes per write to the archive file.  
>> The
>>             blocksize must be a multiple of 512 bytes with a maximum 
>> of
>> 32256
>>             bytes.  A blocksize can end...
>>
>> However, from the tar(1) manpage:
>>
>>       -b blocking factor, --block-size blocking factor
>>                     Set blocking factor to use for the archive.  tar
>> uses 512
>>                     byte blocks.  The default is 20, the maximum is 
>> 126.
>>   Ar-
>>                     chives with a blocking factor larger 63 violate 
>> the
>> POSIX
>>                     standard and will not be portable to all systems.
>>
>> Looks like the later needs updating. BTW, this is current as of around
>> 2003-12-08, haven't looked for more recent changes.
>>
>> If you want larger, non-POSIX blocking factors, you can always install
>> another tar variant from pkgsrc.
>>
>>> the drive is:
>>> st0 at scsibus0 target 6 lun 0: <ARCHIVE, IBM4326NP/RP  !D, 04BK> 
>>> tape
>>> removable
>>> st0: drive empty
>>> st0: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers
>>
>
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Paul Ripke
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