LINEAR RAID vs. LVM

[Tom Metro]

Daniel Feenberg wrote:
> Notice that JBOD has the same rate of failure and storage capacity as 
> RAID 0, but only half the data loss on each failure. We find that 
> significant, but I never see it mentioned in the storage literature, or 
> in newsgroups.

I've always heard the definition of JBOD being quite literal - just a 
bunch of disk. With nothing special about how they are logically 
arranged. But apparently the definition is controversial, as indicated 
in this discussion:

http://en.wikipedia.org/wiki/Talk:RAID#JBOD

with a common second meaning being a concatenation of the physical disks 
into one logical volume.

In Linux RAID terminology that seems to be referred to as Linear mode. 
It seems focus has shifted to LVM for this functionality.

That aside, I'd be curious to know which setup, if either, would prove 
to be more easily (partially) recovered: a two drive Linear array or a 
two drive LVM set, if one of the two drives fails.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/

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