Drive with no partition number

[rvf@linux.wku.edu ( Rob VanFleet)]

I am replacing a drive that I use for /home in a machine.  This drive
was brought semi-up-to-date with some off-site backups, since the drive
it's replacing is dying and is incredibly slow.  The new drive was not
restored by me, and I noticed after installing it in the machine that it
has no partition numbers.  I can mount it as /dev/hdb and everything
works as normal, but I haven't seen that done before, so I'm wondering
if this is something that will cause me problems in the future, or if
it's perfectly normal.

Thanks,
Rob