On Tue, Nov 26, 2002 at 09:32:44PM +0000, Alasdair Kergon wrote:
> If you have 18 extents (PEs) with 6 on each disk numbered:
> disk1: 0 1 2 3 4 5
> disk2: 6 7 8 9 10 11
> disk3: 12 13 14 15 16 17
[More on the numbering LVM* uses, in case that wasn't clear enough.]
Depending whereabouts those extents are on the disk,
the *actual* PE numbers that LVM* assigns could be
completely different (but still consecutive on each disk
inside each segment of the LV) e.g.
disk1: 0 1 2 3 4 5
disk2: 50 51 52 53 54 55
disk3: 8 9 10 11 12 13
And the corresponding logical extent (LE) numbers within the
logical volume run *along* each stripe of the segment in turn:
disk1: 0 1 2 3 4 5
disk2: 6 7 8 9 10 11
disk3: 12 13 14 15 16 17
So in LE terms, the data get striped across 0, 6 and 12, then
1, 7 and 13 etc., equivalent to striping across 3 extents each
6 times bigger, just one per disk viz. [0..5], [6..11] and [12..17].
Alasdair
--
agk@uk.sistina.com
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