Debian install and swap

[Ishwar Rattan <ishwar@pali.cps.cmich.edu>]

The system is a debian derivative. hdb2 is a primary
partition for Linux swap. /etc/fstab has the entry:

/dev/hdb2	none	swap	sw	0	0

but top utility shows 0M swap, and attempt to make it active
with swapon (swapon -a) produces the error:

swapon: /dev/hdb2: Invalid argument

Any ideas?

-ishwar