Hi Todd,
Did you create a file journal (mkfs...) after you executed the command?:

>  # cryptsetup luksOpen /dev/sdb1 lin-bak


Basic steps are:
1) cryptsetup luksFormat /dev/xyz
2) cryptsetup luksOpen /dev/xyz  abc   <---then verify it in /dev/mapper
3) mkfs.ext4 /dev/mapper/abc     <--- i like to use ext4.  Do research on
this journal if you're not clear.
Now that we got it settled.  Come the fun part- automounting:
4) configure your /etc/fstab

5) then configure your /etc/crypttab

Before you reboot your machine, do a tested mount:
>mount -a

-Tam

On Sun, Jul 29, 2012 at 7:37 PM, Todd And Margo Chester <
[log in to unmask]> wrote:

> Hi All,
>
> I can set up "/dev/mapper/lin-bak" with
>
>     # cryptsetup luksOpen /dev/sdb1 lin-bak
>
> but it disappears after I reboot. This messes up my
> crypttab/fstab. Any idea what I am doing wrong?
>
> Many thanks,
> -T
>