OK, what is the purpose of an error message?

You *might* be tempted to say that it's meant to tell you that an error 
has occurred. But actually, it's more than that. It's supposed to tell 
you *what* error occurred! (Usually the fact that _something_ went wrong 
is damn obvious.)

Take the following error message, for example:



PERC 4/SC Controller 0, Array Disk 0:1 Sense Key = 3, Sense Code = 11, 
Sense Qualifier = 0. If this disk is part of a non-redundant virtual 
disk, the data for this block cannot be recovered. The disk will require 
replacement and data restore. If this disk is part of a redundant 
virtual disk, the data in this block will be reallocated.



...WTF?

So... is my data gone or not? If it is, why is it gone? If it isn't, 
what's the problem? (And if there isn't a problem, why are you giving me 
an error message?)

Seriously - YOU'RE THE ARRAY CONTROLLER! You KNOW whether this is part 
of a redundant virtual disk or not. Why can't you just show me only the 
relevant parts of the error message??

Hmm. "The data in this block will be reallocated." What does that *mean* 
anyway? Can you recover the data or not?



As you can see, this is a pretty useless error message. It basically 
says "Event X has happened. If condition Y is true then this represents 
an error, otherwise it doesn't." In other words, this error might not 
even *be* an error. So it's failed purpose #1 - telling you an error has 
occurred. It also utterly fails purpose #2 - WHY is any of this 
happening in the first place? Presumably a block on the disk was 
unreadable - but it doesn't SAY so anywhere.

Sadly, this kind of thing seems extremely common. Developers don't seem 
to think it's important for people to know what an error condition 
actually means or what the implications are.

Oh, did I mention? It's a Dell server.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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