[TriLUG] general RAID questions

Alan Porter porter at trilug.org
Sun Nov 27 21:29:51 EST 2011

JM> Do you have to label all your drive bays at install time?
DB> Oh, labeling that would be a good idea..

Not pointing fingers, but just sharing a funny...

Whoever installed pilot in our space at Sungard labeled the
drives with pretty little stickers.  Like this.

0:0  0:4  1:0  1:4
0:1  0:5  1:1  1:5
0:2  0:6  1:2  1:6
0:3  0:7  1:3  1:7

That would've been awesome-helpful... IF that were actually
the way the drives are laid out.  Instead, they are positioned
like this (basically transposed).

0:0  0:1  0:2  0:3
0:4  0:5  0:6  0:7
1:0  1:1  1:2  1:3
1:4  1:5  1:6  1:7

Guess how we found that out?

On a related note, guess what RAID5 does when you yank an
otherwise fully-functioning drive?  That's right, it keeps on
going.  Thank goodness!  It calls that "degraded mode".  But
everything still runs fine (until a second disk failure).

Once we figured out what wasn't right, we replaced the OK drive
and the RAID system (hardware RAID in our case) rebuilt the array.

And like David said, watching the lights blink is a good way to
make sure you're doing the right thing.

# ɹǝʇɹoԀ uɐl∀

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