7914DS3KPlanning_090710.fm Draft Document for Review March 28, 2011 12:24 pm
76 IBM System Storage DS3500: Introduction and Implementation Guide
Figure 3-23 Relationships between LP and PP
The Logical Volume Manager controls disk resources by mapping data between a simple
and flexible logical view of storage space and the actual physical disks. The Logical
Volume Manager does this by using a layer of device driver code that runs above the
traditional physical device drivers. This logical view of the disk storage is provided to
applications and is independent of the underlying physical disk structure (Figure 3-24).
Figure 3-24 AIX LVM conceptual view
The AIX LVM provides a number of facilities or policies for managing both the performance
and availability characteristics of logical volumes. The policies that have the greatest impact
on performance in general disk environment are the intra-disk allocation, inter-disk allocation,
write scheduling, and write-verify policies.
Best practice: When using a DS3500 Storage System with operating systems that have a
built-in LVM, or if a LVM is available, you need to make use of the LVM.
LP1 LP8 LP9 LP8 LP9
Logical Volume - Iv04 Logical Volume - mirrlv
PP8
PP4 2
PP1 9
PP1 8
PP4 5
PP1 8
PP45
Physical Volume
(/dev/hdisk9)
LP: Logical Partitions
PP: Physi cal Par t i t i o ns
Physical
Partitions
Physical
Partitions
Physical
Partitions
Physical Volume
Physical Volume
Physical Volume
ROOTVG
ROOTVG
Logical
Partitions
Logical Volume
hdisk1
hdisk2
hdisk0
Three physical disks in the box form
a single volume group (rootvg).
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