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Date:      Thu, 7 Jun 2007 14:58:28 -0500
From:      "Rick C. Petty" <rick-freebsd@kiwi-computer.com>
To:        Matthew Hagerty <matthew@digitalstratum.com>
Cc:        freebsd-hardware@freebsd.org
Subject:   Re: Promise TX2300 array not detected.
Message-ID:  <20070607195828.GA368@keira.kiwi-computer.com>
In-Reply-To: <25389.192.85.50.1.1181242998.squirrel@24.56.193.117>
References:  <4662E72B.70003@digitalstratum.com> <4662F5BF.4090709@razik.de> <4663496A.40202@digitalstratum.com> <466718DC.2030600@razik.de> <46674449.6090109@digitalstratum.com> <46678017.6080602@fluffles.net> <21250.192.85.50.1.1181233456.squirrel@mundomateo.com> <20070607164653.GB95991@keira.kiwi-computer.com> <25389.192.85.50.1.1181242998.squirrel@24.56.193.117>

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On Thu, Jun 07, 2007 at 03:03:18PM -0400, Matthew Hagerty wrote:
> 
> My reasoning for a hardware RAID is so I can set it and forget it.  If a
> drive fails (I'm setting up a mirror), I want to be able to just swap the
> drive and carry on without worrying about having to do something at the
> BIOS or OS level (controller should rebuild the mirror).  Performance in

I know of no RAID cards that don't require you to do something at the BIOS
level..  on every card I've seen, if you swap a drive you must go into the
BIOS and tell the RAID card to reconfigure the new drive.  Even on cards
which have hot spares, if you swap the drive you need to tell it about the
new disk.

And with "real" RAID, how do you know if the RAID is having problems?  I
haven't seen good solutions (doesn't mean they don't exist) that didn't
require OS-level drivers and at least some OS-level interaction.  But with
software RAID I can write my own shell scripts that detect unplugged
drives and use S.M.A.R.T. tools to monitor drive health.

Also, if you "feel" safer about somebody's random RAID card, how do you
know there isn't a firmware bug?  At least with software RAID, the
software is likely public and most bugs have been worked out, or you have
some control over the operation.  Unless the RAID card comes with a
warranty to protect your data at all costs (i.e. they will pay you the
value of your data if anything is lost), you're taking a gamble.

> my case is tertiary to reliability and stability.  The TX2300 might have
> been the wrong choice, but you would not have known from reading the
> marketing material...

Marketing also tells me that my 500 GB drive has 500 GB of storage space,
when really it has 500 billion bytes...  All manufacturers are guilty of
using buzzwords to sell their products.  The TX2300 *is* a RAID card after
all, but does it require OS support?  The easy trick to distinguish between
fakeraid and real is whether they list "Supported operating systems" or
package a driver CD.  If it doesn't require OS support, why are they giving
you OS drivers?

> The TX2300 was also blowing errors taskqueue timeout errors
> (http://www.mail-archive.com/freebsd-hardware@freebsd.org/msg01541.html)

Looks like that was in 6.1.  6.2 (-stable) at least doesn't have nearly as
many of these issues.  In fact I haven't seen one crop up since I upgraded
a few months ago.

> on the first machine I had it in, so now I'm a little skeptical about
> using the card.

Try it out and see if you have the same problems.  Perhaps it is fixed in
6.2.

-- Rick C. Petty



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