With GNU tar as the system "tar" , I did backups with "-b 128", which
resulted in a 64K record size on tape.  Our new pax-as-tar accepts
-b 128 on the command line but will never use a buffer larger than 32256
bytes, which results in the kernel being unable to deliver full tape
records to tar, which results in a stream of error messages from at
least some host adapter drivers ("65536-byte tape record too large for
32256-byte user buffer") and unreadable backups.

I understand that ANSI tar allows a maximum blocksize of 32256 -- I
don't understand *why*, but I do understand that that's the standard.

However, it's a serious regression in functionality to not support
larger blocksizes on _read_, leaving people unable to restore old
backups...

-- 
 Thor Lancelot Simon	                                      tls@rek.tjls.com
   But as he knew no bad language, he had called him all the names of common
 objects that he could think of, and had screamed: "You lamp!  You towel!  You
 plate!" and so on.              --Sigmund Freud