Installation guide

3.2. Striped Logical Volumes
When you write data to an LVM logical volume, the file system lays the data out across the un-
derlying physical volumes. You can control the way the data is written to the physical volumes
by creating a striped logical volume. For large sequential reads and writes, this can improve the
efficiency of the data I/O.
Striping enhances performance by writing data to a predetermined number of physical volumes
in round-round fashion. With striping, I/O can be done in parallel. In some situations, this can
result in near-linear performance gain for each additional physical volume in the stripe.
The following illustration shows data being striped across three physical volumes. In this figure:
• the first stripe of data is written to PV1
• the second stripe of data is written to PV2
• the third stripe of data is written to PV3
• the fourth stripe of data is written to PV1
In a striped logical volume, the size of the stripe cannnot exceed the size of an extent.
Figure 2.5. Striping Data Across Three PVs
Striped logical volumes can be extended by concatenating another set of devices onto the end
of the first set. In order extend a striped logical volume, however, there must be enough free
3.2. Striped Logical Volumes
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