Software RAID 5 or something else?

[Bruno Wolff III]

On Fri, Jan 23, 2009 at 14:53:34 -0600,
  Seann Clark <nombrandue at tsukinokage.net> wrote:
>
> The biggest advantage with hardware RAID is you don't need to boot to be  
> able to fix your RAID. Minor difference for some of your more hardcore  
> computer guys, and rather trivial, but it is nice to see your RAID is  
> shattered prior to the kernel barfing on you. Once again, I am sure one  
> of our Software RAID guys will tell me what really happens if the raid  
> is dead to the kernel in a software config.  The other thing I have yet  
> to see is software raid being hot swappable. This is nice because if you  
> are doing more than using the system as a gaming, or personal server,  
> you don't have to power down, replace, reboot, rebuild. I don't know,  
> maybe I am just lazy.

You can modify software raid arrays without rebooting. If a kernel glitch
causes an element to get dropped (which has happened to me recently with
some of the test 28 and 29 kernels) you just add the element back in with
mdadm and it rebuilds while the system is running.
You can mitigate hot swap needs by having spare drives already plugged in.
You'll still need to do a swap eventually, but it can be deferred to a
convenient time.