On 03/06/2013 07:25 PM, Roe Peterson wrote:
   dd doesn't
change blocking, it's just a byte-by-byte dump, unless
 you specify otherwise. Tar, on the other hand, looks for files. 
 Actually, dd uses 512-byte blocks by default,and always has. At least
 since V6, anyway... 
 
Logical blocks, yes.  But AFAIK, it has no capability to reproduce the
size of physical blocks when doing a tape-to-disk transfer.  How could
it?  Unix has no way to specify the size of variable-sized physical
blocks on disk.
--Chuck