[CentOS] Best way to backup and entire machine??

[Les Mikesell]

John Plemons wrote:
> I want to mirror a Centos box, not having done this before, I'm looking 
> for guidance.
> 
> What is the best way to perform this task, I have a running webserver, a 
> single external IP address to the website, and wanted to protect myself 
> should the server go down. My though would be a mirror of that 
> webserver, running in background, if the main server dies, then just 
> move the mirror in place, change the IP and go on...  Limiting down time...

There are several approaches, depending on how you want to trade expense 
and effort against possible downtime - and whether your site is 
approaching the point where you need a load-balanced farm of servers and 
possibly redundant sites.

The easiest plan with the least to go wrong is probably to use RAID1 
mirrored/swappable drives with a spare chassis, and also do nightly 
backups.  The most likely failure will be a disk drive, handled 
transparently by the mirror until you can replace it.  Next most likely 
would be the power supply/motherboard which you handle by swapping the 
disks to your spare with a small amount of downtime.  Next would be an 
operator or software error that erases or corrupts your disks.  For that 
you have to restore from your last backup with a much longer downtime.

You can keep the spare server in sync with DRBD and fail over 
automatically with heartbeat at the expense of more complexity but you 
still need backups for the error scenaro.

-- 
   Les Mikesell
    lesmikesell at gmail.com