Choosing the right RAID was Re: [ILUG] Wee nas box

[Pádraig Brady]

Gavin McCullagh wrote:
> Hi,
> 
> On Fri, 20 Nov 2009, Pádraig Brady wrote:
> 
>> Hardware RAID is worse than software RAID right?
>> See the last paragraph here:
>> http://www.pixelbeat.org/docs/hard_disk_reliability/#RAID
> 
> This is a question I come to regularly.  Opinion seems very divided and I'm
> not sure a general answer to the question exists.
> 
> I would side with good software raid (such as linux md) over cheap hardware
> RAID.  However battery-backed hardware RAID seems valuable and I've yet to
> see a solution to that with software RAID -- apart from a UPS perhaps.
> I've also repeatedly heard the performance benefits of hardware RAID are
> considerable (I'm not sure I've ever seen data to back this up though).
> 
> There are those who are critical of md too:
> 
> 	http://www.ashtech.net/~syntax/blog/archives/53-Data-Scrub-with-Linux-RAID-or-Die.html
> 	http://www.nber.org/sys-admin/linux-nas-raid.html

The thing is I'd trust it more than some random card firmware,
and also you're not tied to that card's firmware.

> The other question I have is whether to trust RAID5.  There appear to be
> some people who really think not and:
> 
> 	http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt

To add to the argument of another disk breaking during a rebuild:
http://blogs.zdnet.com/storage/?p=162

cheers,
Pádraig.