Gigabyte GA-VM900M caveats

[Daniel O'Connor]

On Wednesday 23 May 2007 12:17, Bruce M. Simpson wrote:
> Thanks for the affirmation that I'm not alone in this. The whole
> point of RAID being supported by platform firmware is to facilitate
> booting from it even if disks fail.

Yes, I was pretty pissed off when I found out about it. I was even more 
pissed off at Epox's weak response :(

> > When I asked my motherboard vendor about this they suggested I
> > switch to SATA mode (to boot off one disk) or to put another disk
> > in and rebuild... Not exactly good for unattended use.
>
> Summary: Avoid VIA software RAID like the plague.

Yep.
The JMicron RAID in my Core 2 Duo system seems OK. 

That said all of these software RAID implementations seem to suffer from 
a serious limitation - if the disk fails temporarily and the array 
becomes degraded and you then subsequently reboot it will see 2 arrays 
and can boot off the stale one.

I would expect a more sensible implementation where it would scan the 
disks and if it sees 2 disks with the same array ID but differing ages 
it should ignore the older disk.

This assumes that the RAID code increments the generation number (or 
whatever) when it notes the array is degraded.. I would hope so but 
maybe I'm wrong.

I have been bitted by this several times especially in SATA as it seems 
more likely to get temporary failures (especially with dodgy PHYs like 
Marvell)


> Yes, utter crap, and a waste of valuable time.

Yeah, I stumped up for 3ware in the end.

Not that they are MUCH better, I have several pending issues with them,  
but so far as I can see they are the only manufacturer of 2 port 
hardware RAID cards.

> [Normally I have been running 7-CURRENT on that machine, with the
> JMicron card, so up until now this hasn't been an issue, but this is
> what kicked off the whole shooting match in the first place, and I
> need to be able to multi-boot Windows "Longhorn" Server and Gentoo
> Linux for the work I'm going to be doing.]

I have Windows XP and FreeBSD 6.2 on my Core 2 Duo/JMicron system. sos@ 
is looking at a problem in current (it doesn't see my disks).

I tried Ubuntu on this system but its dmraid doesn't grok the JMicron 
metadata properly (not to mention that dmraid does almost no error 
handling and so I am loathe to use it)

> I wonder if people have had better experiences with JMicron. I am
> encouraged by the work Scott Long has begun, although that is going
> to take time to bear fruit. I can't burn too much time on this
> though, I needed a working server today.

I only have 1 JMicron system and it works OK so far (modulo my issue 
in -current).

The last good, cheap RAID card I used was a Promise FT100/TX2, alas it 
is PATA only and they don't sell them any more.

-- 
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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