setup software raid
-------------------
2007-07-29

To create new RAID 1 (THIS WILL ERASE YOUR DRIVES):

1.  put identical drives in machine
2.  fdisk to create identical primary partitions, type 1.
3.  mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1
4.  answer y to create array (it begins sync, cat /proc/mdstat for progress)
5.  mke2fs -j -l /vmguests /dev/md0
6.  mount in fstab:
    LABEL=/vmguests     /vmguests     ext3     defaults    1 2
7.  mount -a
8.  ll /vmguests and you probably see lost+found

To re-create an existing RAID 1 without destroying data
(MAKE SURE NO CHANGES WERE MADE TO EITHER DRIVE IN THE MIRROR:

1.  create /etc/mdadm.conf
---BEGIN---
DEVICE /dev/sda1 /dev/sdb1 (or whatever your drives are)
ARRAY /dev/md0
----END----
2.  mdadm --assemble /dev/md0

To re-build an existing RAID 1 with one good drive and a bad drive replacement
(MAKE SURE THE 'GOOD' DRIVE IS THE ONE WITH DATA YOU WANT TO KEEP!)

1.  create /etc/mdadm.conf
---BEGIN---
DEVICE /dev/sda1 (your 'GOOD' drive)
----END----
2.  mdadm --assemble /dev/md0


This might work better
----------------------

-R run
mdadm --assemble md0 -R /dev/sda1
vi /etc/fstab
	/dev/md0 /vmguests ext3 defaults 1 2
mount /vmguests
cat /proc/mdstat (check status)
mdadm --manage /dev/md0 --add /dev/sdb1
cat /proc/mdstat (should see rebuilding)
fdisk /dev/sda & sdb, set type "t" to "fd"