Re: [MLUG] software raid conifg - fedora

[Dave Lloyd <EMAIL:PROTECTED>]

On Thu, 10 Nov 2005, Shawn Parker wrote:

> when configuring a software raid in fedora core 4, how do you set up
> an "extra" disk for raid1? i have 3 80GB drives in my server. i would
> like to set up a raid1 (mirror) of 2 drives and use the 3rd as an
> extra drive incase one fails?
> 
> how does one do this? do i configure the raid1 using all 3 drives and
> simply set the "extra drive" parameter to 1? do i clone hda to hdc and
> hdd so that each drive is *exactly* the same, first?
> 
> i have no problem setting up a standard raid1 with just 2 drives...but
> i'm a little confused when using a 3rd for an extra in fedora's
> partition manager.

Not that I have an answer, but I've got a question:  why do you want to
do this?  It's my experience that the second drive will not fail until
you can replace the first failed drive unless:

1) There's a hardware problem where drives of a certain age fail
   (mechanical, de-soldering of chips, etc.).
2) Outside environmental influences.

My personal opinion, and my experience backs me up here, is that
operator error that causes data loss is FAR more likely than a disk
failure.  You're better off doing a weekly backup to your third disk and
sticking it in a file drawer than having a hot spare that can come in
and replace a failed volume.

Oh, and please, please do not mirror swap.  Mirroring really cuts write
performance, and if you start to write to swap, well, things will begin
to suck much more than a "normal" condition under which you write to
swap.

--dlloyd

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