On Tue, 11 May 2004, Allan Wind wrote:

> On 2004-05-11T15:29:46-0600, scott.marlowe wrote:
> > The other nice thing about the LSI cards is that you can install >1 and 
> > the act like one big RAID array.  i.e. install two cards with a 20 drive 
> > RAID0 then make a RAID1 across them, and if one or the other cards itself 
> > fails, you've still got 100% of your data sitting there.  Nice to know you 
> > can survive the complete failure of one half of your chain.
> ... unless that dying controller corrupted your file system.  Depending
> on your tolerance for risk, you may not want to operate for long with a
> file system in an unknown state.

It would have to be the primary controller for that to happen.  The way 
the LSI's work is that you disable the BIOS on the 2nd to 4th cards, and 
the first card, with the active BIOS acts as the primary controller.

In this case, that means the main card is doing the RAID1 work, then 
handing off the data to the subordinate cards.

The subordinate cards do all their own RAID0 work.

mobo ---controller 1--<array1 of disks in RAID0
.....|--controller 2--<array2 of disks in RAID0

and whichever controller fails just kind of disappears.

Note that if it is the master controller, then you'll have to shut down 
and enable the BIOS on one of the secondardy (now primary) controllers.

So while it's possible for the master card failing to corrupt the RAID1 
set, it's still a more reliable system that with just one card.

But nothing is 100% reliable, sadly.

> Btw, the Intel and LSI Logic RAID controller cards have suspeciously
> similar specificationsi, so I would be surprised if one is an OEM.

Hmmm.  I'll take a closer look.

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