Question: I have 2 harddrives in my system, managed by LVM

```
vg1 (on /dev/sda2)
lv_root
lv_swap

vg2 (on /dev/sdb2)
lv_root
lv_swap

```

I removed the sdb HDD and when booting it has gotton slower and drops into debug mode and dmesg shows me:

```
dracut: Scanning sda2 for LVM logical volumes vg1/lv_root vg1/lv_swap vg2/lv_root vg2/lv_swap
dracut: inactive /dev/vg1/lv_swap inherit
dracut: inactive /dev/vg1/lv_root inherit
Volume group vg2 not found
Skipping volume group vg2
dracut: Warning: No root device "block:/dev/mapper/vg_myname-lv_root" found
dracut: /dev/mapper/vgmyname-lv-swap" not found.

```

It's the same issue as here: <http://forums.fedoraforum.org/showthread.php?t=265470>

**Answer**:

The problem was that the bootloader looked for the removed swap logical volume. All I had to do was to edit `grub.conf`and reboot. 

Just to be sure I also deactivated the drive in KDE's 'Disk Utility'.

Answer: 
Why do you need to rebuild the pool? How much data is actually contained in the pool? That will have a greater effect on your migration strategy than anything else. If it is possible to place the data on a single disk (e.g. 1 or 2 Terabytes), I'd do that rather than risk a stripe of unmirrored disks. But again, it depends on how much data needs to move.
Your steps seems to amount to "leap frogging" the mirrors which are already in place. That will probably not "undo" the reduplication as those attributes will probably continue forward as the mirror sets rebuild. You may need to consider application-level replication/copying between the deduped vs. non-deduped pools in order to expand-out the actual file instances.