[nzlug] Raid

[Steve Holdoway]

On Thu, 27 Sep 2007 12:08:46 +1200
Daniel Lawson <daniel at meta.net.nz> wrote:

> Dirk Pilat wrote:
> > Hiho,
> >
> > after the discussion about dual booting with raid/fakeraid, may I ask
> > whether there is any benefit for me as a homeuser to have a raid
> > setup? I regularly backup my homefolder and the HD that contains the
> > data accessed by all my OSS's (music/movies/phothography).
> >
> > What benefit would Raid give apart from extra data security (and maybe
> > speed)? 
> 
> Backups and RAID are also orthogonal technologies.  RAID doesn't protect
> you against your power supply catching fire and burning your entire pc,
> harddisks included.  RAID protects you from single (in some cases
> multiple) disk failures.  Backup protects you from user stupidity
> ("whups, I just did rm -rf * ~ instead of rm -rf *~"), and from
> entire-machine/environment failure[1]
> 
> Other than that, if you have regular backups[2] for all your data you
> care about[3], the main benefit RAID gives you over backup-and-reinstall
> is that your system is available immediately after a disk loss, as
> opposed to having to wait until you can buy a new disk, then install
> your OS, setup your applications, etc.  For business cases the benefits
> are massive - a days downtime could cost a business a lot of money, and
> the chances of a new server + OS install + data restore happening in a
> day are pretty slim. More like 3 to 7 days, realistically.
> 
> For a home user, unless you can't afford to have a machine down, or
> don't want to, or aren't skilled enough to rebuild your systems
> yourself, then a well maintained backup is probably just fine.
> 
> [1] assuming your backups are stored elsewhere; if they are on the
> machine next to the original, and your house burns down, you just lost
> everything.
> [2] and they actually work, and you can restore from them ...
> [3] and you make sure you keep this list of data up to date ...
> 
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Couldn't have put it better myself. Most people forget that backups are primarily a protection against mistakes, not disasters.

Your [2] reminds me of the time I took over an Unisys unix box ( famous for the 'power fa' message on the console on power down ) and the system crashed. Turned out my predecessor had set up overlapping partitions...

This was when I found out the backups had never worked either.

Steve.