[rescue] Re: Small RAID array setup

[Gregory Leblanc]

On Mon, 2003-06-30 at 18:17, rescue-request at sunhelp.org wrote:
> From: Rip Loomis <rip at flagon.com>
> To: Curtis H. Wilbar Jr. <rescue at hawkmountain.net>, The Rescue List
<rescue at sunhelp.org>
> Subject: [rescue] Re: Small RAID array setup
> Date: 30 Jun 2003 16:41:08 -0400
>
> > The one thing to keep in mind about using hardware raid of any sort,
> > is keeping a spare controller....  as if your controller dies, it
> > stands directly between you and your data and no amount of RAID 0,
> > RAID 0+1, or RAID 1+0 will help.
>
> Actually, it's worse than that AFAIK:  One not only needs another
> RAID controller handy (for hardware RAID) but also a readable backup
> of the RAID config.  If my primary DAC960 crashed then I have another,

Or at the very least, intimate knowledge of the RAID config, and the way
that the RAID controller works.  I'm not sure how detailed you can get
with the DAC 960, but with some software RAID systems, you can do
anything you might want.

> but I don't think I have a backup of the RAID config from the primary.
> If I try to initialize a new DAC960 with the same 4 drives that already
> have data on them, it will want to reformat them as a new (!) array.
> This wouldn't be quite what I wanted at that point...
>
[snip]
> So given the *BSD, Linux, and Solaris software RAID implementations
> out there, has anyone had any luck with recovering such a system
> after failure of the boot device (IOW, having to reconfigure software
> RAID on the same/a different system and trying to recover data that
> was in the software RAID array)?  I'm curious to know...

Yep.  I've done about what the other poster (uhm, Espen Randen, who I've
not heard of before) has, only using the Software RAID tools on Linux.
I've also taken a RAID 5 array that was hosted on a hardware RAID
controller set it up using the software RAID tools on linux, and copied
the data off while we waited for a replacement controller to arrive.
Now that was some great fun.  :)
	Greg

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