root disk mirroring using mdadm

[Bipin Baghele]

Hi All,
We have several HP Proliant servers (DL series as well as blade with no
SMART Array RAID controller) running Redhat 3 & 4 Ent version as well
SLES 9. I am planning to mirror the root disk to another disk on same
server using "mdadm" command feature in Linux. I compiled all the steps
but not yet tested. Waiting for hardware availability.
Meanwhile, wanted to check the feedback on mdadm from this list...
like
1. How is the process?. So far looks simple....
2. generally how long it takes to mirror say 72gb drive, approximate
figure.
3. How reliable is the software mirroring in actual use in
dev/qa/test/prod env.
4. Any potential issues.
5. Do I need to be in single user mode or rescue more or multiuser mode
is perfect?
6. Any issues, dealing with one disk failure? like online replacement
etc...
*------command-----------------
# mdadm -C /dev/md0 --level=raid1 --raid-devices=2 /dev/hda1 /dev/hdb1
(to configure mirroring)
# mdadm --detail /dev/md0 (to check the status)
*----------------------------------
Will appreciate your feedback.