3.7. mapping modes (linear/striped)
The administrator can choose between a couple of general strategies
for mapping logical extents onto physical extents:
Linear mapping will assign a
range of PE's to an area of an LV in order eg., LE 1 - 99 map to
PV1 and LE 100 - 347 map onto PV2.
Striped mapping will interleave
the chunks of the logical extents across a number of physical
volumes eg.,
1st chunk of LE[1] -> PV1[1],
2nd chunk of LE[1] -> PV2[1],
3rd chunk of LE[1] -> PV3[1],
4th chunk of LE[1] -> PV1[2],
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and so on. In certain situations this strategy can
improve the performance of the logical volume.
| LVM 1 Caveat |
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LVs created using striping cannot be extended past
the PVs they were originally created on in LVM 1.
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In LVM 2, striped LVs can be extended by concatenating
another set of devices onto the end of the first set. So
you can get into a situation where your LV is a 2 stripe
set concatenated with a linear set concatenated with a 4
stripe set. Are you confused yet?
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