[ILUG] Why RAID

[Rick Moen]

Quoting Paul Mc Auley (paul at peema.org):

> I'm a little less enthusiastic about soft RAID. While you can get some
> of the benefits of hard RAID that way, I tend to feel it's a bit less
> likely to recover from a serious disk failure...

Linux "md"-driver software RAID's gotten really good, Paul.  It's really
become very reliable, by degrees, since the early days when we all were
very leery of it.  I've been impressed.  Managing boot is a pain, and
rebuilding the array loads down the system really heavily, but the
recovery function is definitely there.

> ...and doing stuff in the main CPU rather than on a dedicated
> controller is going to generate overheads.

I used to make that argument all the time.  However, then I realised
that a typical Linux deployment has the CPU severely underused.  Don't
forget, commodity hardware is performance-balanced (to the extent that
can be said of it) with an eye towards the staggeringly inefficient CPU
demands of Win2k/XP.  Typically, the CPUs on Linux systems spend a whole
lot of time doing very little.

> That said, the sort of servers that do RAID properly are generally more
> suited to a data centre environment than a domestic one.

Oh, I don't know:  The VA Linux model 501 server in my living room
whines like a banshee (er, "bean sidhe"), and I can't help thinking my
domestic bliss would be better served by a pair of nice large, _quiet_,
low-power SATA drives in RAID1 configuration.

-- 
Cheers,     "In 1993, the World-Wide Web was an infosystem based on hypertext.
Rick Moen    In 1994, the World-Wide Web was an infosystem based on hype."
rick at linuxmafia.com                                       -- Lars Aronsson