redundant-servers question

[teddy mills]

I have servers I need to make redundant.
Live PC and a backup PC, both exactly the same hardware.
Servers are Gentoo with RAID1.

If I have any problems with any of the live servers then I pull the 
network plug, and drop that network cable into its exact-copy backup server.

I thought about using rsync, to keep the backup servers the same as the 
live servers.
The weak point is the rsync complexity. If I miss even one important 
file for rsync, then it renders the whole solution almost useless.
(ie. with 1000% confidence, I should be able to remove the live server 
at any time, and replace it with the backup.)
As well, I would have to do a worst-case scenario test..ie..replace a 
live server with the backup.

I would much prefer to use mdadm's rebuilding feature and hot-swapping 
drives. (once per 24 hours, or as needed)

LIVE PC.
RAID1 with hotswap 2 drives.DRIVE-A and DRIVE-B

BACKUP PC with 1 hotswap drive DRIVE-C.

Everyday, hotswap exchange DRIVE-B and DRIVE-C.
fdisk /dev/DRIVE-B, and let mdadm rebuild it.
Leave the working backup in the backup PC.

Using this method, I am virtually guaranteed that the backup servers are 
exactly the same as the live servers.
Only problem with this solution, is that every day I am breaking and 
rebuilding the raid.
With no room for errors. A LOT more risky than just letting the RAID1 
run alone.

Any ideas about this?
TIA!

/teddy

 
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