[BlueOnyx:11228] MD RAID device state="clean, degraded" -- how to fix

[Bob Wickline]

I have a Dell server that I installed 5108.  It has two (2) 1GB drives 
and one (1) 2GB disk.  When I installed it, I used the option to mirror 
(soft RAID) across the drives but when I did it used all three drives.  
I used "mdadm" to fail and remove the third (2GB) drive.  (I did not 
want it part of the root mirror)  Now the device shows "clean, degraded" 
when I list it with mdadm:

# mdadm --detail /dev/md0
/dev/md0:
         Version : 1.0
   Creation Time : Fri Jul 20 07:38:36 2012
      Raid Level : raid1
      Array Size : 511988 (500.07 MiB 524.28 MB)
   Used Dev Size : 511988 (500.07 MiB 524.28 MB)
    Raid Devices : 3
   Total Devices : 2
     Persistence : Superblock is persistent

     Update Time : Tue Aug 28 16:25:57 2012
           State : clean, degraded
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0

            Name : localhost.localdomain:0
            UUID : 8b68d22d:4566147a:621a50a4:6d016578
          Events : 325

     Number   Major   Minor   RaidDevice State
        0       8        1        0      active sync /dev/sda1
        3       8       17        1      active sync /dev/sdb1
        2       0        0        2      removed
#

How do I recover from this?