Linux software RAID 1 - root filesystem becomes read-only after a fault on one disk

Linux software RAID 1 locking to read-only mode

The setup:  
Centos 5.2, 2x 320 GB sata drives in RAID 1.

 - /dev/md0 (/dev/sda1 + /dev/sdb1) is
   /boot
 - /dev/md1 (/dev/sda1 +
   /dev/sdb1) is an LVM partition which
   contains /, /data and swap partitions

All filesystems other than swap are ext3

We've had problem on several systems where a fault on one drive has locked the root filesystem as readonly, which obviously causes problems.
    [root@myserver /]# mount | grep Root
    /dev/mapper/VolGroup00-LogVolRoot on / type ext3 (rw)
    [root@myserver /]# touch /foo
    touch: cannot touch `/foo': Read-only file system

I can see that one of the partitions in the array is faulted:

    [root@myserver /]# mdadm --detail /dev/md1
    /dev/md1:
    [...]
              State : clean, degraded
     Active Devices : 1
    Working Devices : 1
     Failed Devices : 1
      Spare Devices : 0
    [...]
        Number   Major   Minor   RaidDevice State
           0       0        0        0      removed
           1       8       18        1      active sync   /dev/sdb2
           2       8        2        -      faulty spare   /dev/sda2


Remounting as rw fails:

    [root@myserver /]# mount -n -o remount /
    mount: block device /dev/VolGroup00/LogVolRoot is write-protected, mounting read-only

The LVM tools give an error unless --ignorelockingfailure is used (because they can't write to /var) but show the volume group as rw:

    [root@myserver /]# lvm vgdisplay
    Locking type 1 initialisation failed.
    [root@myserver /]# lvm pvdisplay --ignorelockingfailure
      --- Physical volume ---
      PV Name               /dev/md1
      VG Name               VolGroup00
      PV Size               279.36 GB / not usable 15.56 MB
      Allocatable           yes (but full)
      [...]
   
    [root@myserver /]# lvm vgdisplay --ignorelockingfailure
      --- Volume group ---
      VG Name               VolGroup00
      System ID
      Format                lvm2
      Metadata Areas        1
      Metadata Sequence No  4
      VG Access             read/write
      VG Status             resizable
      [...]
   
    [root@myserver /]# lvm lvdisplay /dev/VolGroup00/LogVolRoot --ignorelockingfailure
      --- Logical volume ---
      LV Name                /dev/VolGroup00/LogVolRoot
      VG Name                VolGroup00
      LV UUID                PGoY0f-rXqj-xH4v-WMbw-jy6I-nE04-yZD3Gx
      LV Write Access        read/write
      [...]

In this case /boot (seperate RAID meta-device) and /data (a different logical volume in the same volume group) are still writtable.  From the previous occurances I know that a restart will bring the system back up with a read/write root filesystem and a properly degraded RAID array.  


So, I have two questions:

1) When this occurs, how can I get the root filesystem back to read/write without a system restart?

2) What needs to be changed to stop this filesystem locking?  With a RAID 1 failure on a single disk we don't want the filesystems to lockup, we want the system to keep running until we can replace the bad disk.