RAID and /boot partitions

[redhatdude at bellsouth.net]

-------------- Original message ----------------------
From: Bill Davidsen <davidsen at tmr.com>
>
> redhatdude at bellsouth.net wrote:
> > Hi,
> > When creating a RAID 1 in F9.
> > Does it make sense to make the /boot partition on both discs a RAID too?
> I have /boot and / as RAID 1 (dm-0 and dm-1). If I disconnect one of the 
> drives, the computer freezes. Isn't the RAID supposed to keep it running?
> > I'm really new to this, so any help is appreciated.
> > 
> Are you sure /boot is on a raid partition, and not on a dm pseudo 
> device? If you created a partition on your drives, made a raid-1 of the 
> two partitions (100-200MB is good), and then did whatever with the rest 
> of your disk, you should be fine.
> 
> If you made one huge raid array and used dm to break it up, you are not 
> fine. Do "cat /proc/mdstat" and see that there is a small raid-1 for 
> boot, and "df" to check that /dev/mdX is mounted on /boot. If that's the 
> case you should be good, otherwise you probably don't boot off one drive.
> 
> NOTE: your BIOS may not boot off the 2nd drive if the 1st drive is 
> present and has data errors, should if the 1st drive is dead. Some BIOS 
> do, some don't.
> 
> -- 
> Bill Davidsen <davidsen at tmr.com>
>    "We have more to fear from the bungling of the incompetent than from
> the machinations of the wicked."  - from Slashdot

This is the output of df.

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/md1             470535632   3951984 442681744   1% /
/dev/md0                 99099     12499     81484  14% /boot
tmpfs                  2032168        48   2032120   1% /dev/shm

And this is the output of cat /proc/mdstat 
Personalities : [raid1] [raid6] [raid5] [raid4] 
md0 : active raid1 sdb1[1] sda1[0]
      102336 blocks [2/2] [UU]
      
md1 : active raid1 sda3[0] sdb3[1]
      478038080 blocks [2/2] [UU]
      
unused devices: <none>


I have two drives with /boot and /
If I unplug the first one, the system remains up and running. If I however unplug the second one, the system becomes unstable, X crashes, and eventually the system becomes irresponsive.
Why does this happen with one disk only?
Thanks,
EJ