Very Computer

I want to backup machine localhost to machine remotehost.
I want to do that with dump and ssh. The backup is initiated
on the host localhost with:

dump 0ubf 64 - / | /bin/dd bs=64k  | ssh remotehost "/bin/dd bs=64k
of=/dev/tape"

This works as expected and the tape on remotehost starts spinning.

When I read the dump back (locally) on remotehost with the
commmand:

restore if /dev/tape

I'll receive the following error message:

Tape block size (1) is not a multiple of dump block size (1024)

I couldn't find any explanation for that. So I tried the following
things. I wrote instead to the tape to a file on remotehost with the
command:

dump 0ubf 64 - / | /bin/dd bs=64k  | ssh remotehost "/bin/dd bs=64k
of=/tmp/backup"

and read it back with

restore if /tmp/backup

And it worked. I wrote (locally) on remotehost:

dump 0uf  /dev/tape  /tmp

a tape an read it with

restore if /dev/tape

and ofcourse it worked too. So I have somehow contradictionary
evidences. Any ideas?

Thanks for help, Markus Wildi