[Klug-general] Software Vs Hardware Raid

[Karl Lattimer]

On Thu, 2008-07-03 at 15:30 +0100, Peter Frost wrote:
> Peter Childs wrote:
> > I am trying to get the pros and cons straight in my mind.
> > 
> > Software Raid
> > 
> > Easy to configure
> > Cheap Just put more drivers in your machine
> 
>   + Not tied to a single brand of RAID controller (you can replace your 
> SATA controller/motherboard with a different one, put the array into 
> another machine, etc.); my understanding is that with hardware RAID you 
> generally have to stick to one chipset or set of chipsets, otherwise 
> your array will stop working. I have always used software RAID though so 
> I may be mistaken.

This is a fairly accurate assessment. However you can also use a
hardware+software combination which can be beneficial if the hardware
doesn't support all raid modes.

For instance if you have 3 hardware raid controllers of whatever
chipset, each one has two disks on it using raid cloning, then you use
raid6 across the 3 arrays you have the benefit of raid6 and the benefit
of hardware raid.

It all depends on your circumstances which is best to suit you.

BTW: Sata is hotswappable if you take a look at the sata power and sata
data connectors you'll see that they have some shorter pins, the disks
can spin down and park in a few seconds and they can easily be reloaded
now on insertion, so you can in theory insert different disks into the
array and libata will work fine now.

At least this is my understanding after some interesting changes were
made to libata over a year ago. Of course its always best to have
hardware which supports this explicitly.

BR,
 K