writing large tape blocks

writing large tape blocks

Post by Nicolas A Nem » Fri, 13 May 1994 04:11:45



Hi There,

I am having a problem in getting a scsi tape device write blocks larger
than 64K...

It will write, BUT it breaks the block up into 64K blocks
plus a remainder block...which causes me problems in seeking...

Thanks in advance for any assistance...


 
 
 

writing large tape blocks

Post by Tom Ploegmake » Wed, 18 May 1994 00:22:50



Quote:>I am having a problem in getting a scsi tape device write blocks larger
>than 64K...

>It will write, BUT it breaks the block up into 64K blocks
>plus a remainder block...which causes me problems in seeking...

As far as i know this is documented behavior for sunos 4.1....
But we use 4.1e on a sparcengine, and even 65k block wont work. I
have to go down to 32k. I do not get the breakup, but i get io errors.

Anyone knows why?

--


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                        phone: -31 20 5922035

 
 
 

writing large tape blocks

Post by ld kell » Wed, 18 May 1994 04:07:58




>>I am having a problem in getting a scsi tape device write blocks larger
>>than 64K...

>>It will write, BUT it breaks the block up into 64K blocks
>>plus a remainder block...which causes me problems in seeking...

>As far as i know this is documented behavior for sunos 4.1....
>But we use 4.1e on a sparcengine, and even 65k block wont work. I
>have to go down to 32k. I do not get the breakup, but i get io errors.

>Anyone knows why?

See the mtio man page.  65535 is the released upper limit.  

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Arden Hills, MN         |

 
 
 

writing large tape blocks

Post by Frank Evan Perdica » Thu, 19 May 1994 01:00:46




>>I am having a problem in getting a scsi tape device write blocks larger
>>than 64K...

>>It will write, BUT it breaks the block up into 64K blocks
>>plus a remainder block...which causes me problems in seeking...

>As far as i know this is documented behavior for sunos 4.1....
>But we use 4.1e on a sparcengine, and even 65k block wont work. I
>have to go down to 32k. I do not get the breakup, but i get io errors.

>Anyone knows why?

That is an easy one.

The ring buffer size in various 9 track SCSI tape drives
Sun sold is ( was?? ) only 64k.  This was certainly the truth a
few years back when I worked with the 9 track drives a bit.

Hardware limitation begat software limitation.  Might be called a
bug today.

--
Frank Evan Perdicaro                    Dainippon Screen Engineering of America
 Legalize guns, * and cash...today.    3700 Segerstrom Ave


 
 
 

writing large tape blocks

Post by <fletc.. » Wed, 18 May 1994 23:12:01


Several years ago (SunOS 4.0.3) we bought a 1/2 inch SCSI tape drive to
read seismic field tapes.  These tapes had physical records sized anywhere
from 100,000 bytes to 3,500,000 bytes.  To get our Sparc 1+ to read those
records we had to purchase a software driver and re-make the kernal.  The
source of information about the driver (an independant software provider)
said they had had no problems with record length limitations with any
hardware other than that manufactured by Sun which had a hard 64K limit
coded in.

The driver was obtained from:

     MicroTech Conversion Systems
     940 Industrial Avenue
     Palo Alto, CA    94303

     tele:  1-415-424-1174

This information is 3 years old.  It might still be a start.

Obviously, there is no affiliation between us and MicroTech other than
we purchased something from them that solved our problem.

Reid