Communications between 3B2 and Sun via afio

[John D Fulreader]

Problem with afio

	I am having problems using afio when archiving data across a network.
 I am attempting to write from an AT&T 3B2 600 running System V 3.2.1  onto a
 reel to reel tape device physically mounted on a Sun 3/280 running SunOS 4.0.3.
 TCP/IP is used across an Ethernet network.  When attempting to read an archive,
 spurious "BAD MAGIC NUMBER" errors occur.  The archive can be read on the local
 Sun so the archive file is not corrupt.  The problem arises when the 3B2 reads
 the archive off the pipe.  

	In attempting to solve this problem I have observed: 

		- there is no relationship between the type of file
 		  (binary,text,etc) and the corruption of that file 

		- varying the archive block size does not seem to 
 		  improve the problem (tar uses large block size to 
		  allow it to work across a communications channel 
		  that may not maintain block size) 

		- the problem improves when the  -c buffer count  
 		  option is used(afio recommends a large count when 
	          using a streaming magnetic tape drive)

		- improvement when a wait loop is used in the remote
 		  process that sends archive data through the pipe to 
		  the local afio process

		- the problem is worse with greater load on the 
		  network


	I would appreciate any suggestions or information concerning this 
 problem.