M. Adam Davis wrote:

> * RAID 1 (Mirroring) is no replacement for a good backup

I read that often. It's true, but in most contexts it's a strawman. RAID1
is no replacement for a good backup strategy, and a good backup strategy is
no replacement for RAID1. They are in different categories, and complement
each other. So mentioning the obvious when nobody suggested that RAID1 was
a replacement for a good backup strategy is definitely what classifies as a
strawman.

> He also gives interesting statistics about hard drive failures and RAID
> support issues, but he never mentions RAID card failures, and HD
> failures in RAID arrays.  Sounds like either they don't track it (ie,
> it's not frequent enough to track) or the numbers weren't conducive to
> his argument.

I think that maybe the probabilities of RAID controller failures are low,
but if it happens and you're not in a pro shop that has dozens of systems
with the same controller and have a few replacement controllers on hand,
you're pretty much in a bad spot. I think it's a bad idea for a consumer or
small shop to be so dependent on a single piece of hardware for access to
the data. (That would of course be different if there was a standard how to
mark RAID arrays, so that I could take the disks and connect them to any
RAID controller. But that's just wishful thinking...)

> Still, his points are valid - most people, even those that think they
> need one, don't need a RAID array.

How do you (or anybody, for that matter) know what "most people" need? In
that same vein, I could say that you have a hard time figuring out what
/you/ need (just as me, FWIW :) 

I think RAID1 is something that many people could need and could (maybe
even should) have. Even though it's more difficult to talk someone through
rebuilding a RAID1 array after a hardisk failure than talk him through
boiling a pot of tea, it's definitely less difficult than reinstalling the
system (not to the state it was in when it left the dealer, but to the
state it was before the crash) and bringing the data back. Even with a
backup. 

The major difficulty in rebuilding a RAID1 array is replacing the disk --
which needs to be done anyway, RAID or not. Most people who can do that and
are able to restore a backup onto it are also capable of performing the few
steps of rebuilding a RAID1 array. In that sense, I think the article was
mainly crap, written exclusively from the perspective of a service provider
(as someone else already stated) and completely forgetting the user of the
system and the data and configurations on it.

Gerhard

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