LVM Volume Group Dynamic LUN Expansion (DLE) and Contraction (DLC) (September 2009)

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Alloc PE 76770
Free PE 0
…
VG Version 2.1
VG Max Size 32t
VG Max Extents 4194304
--- Logical volumes ---
LV Name /dev/vg1/lvol1
LV Status available/syncd
LV Size (Mbytes) 204720
Current LE 25590
Allocated PE 76770
Used PV 3
--- Physical volumes ---
PV Name /dev/disk/disk46
PV Status available
Total PE 25590
Free PE 0
…
PV Name /dev/disk/disk47
PV Status available
Total PE 25590
Free PE 0
…
PV Name /dev/disk/disk48
PV Status available
Total PE 25590
Free PE 0
Online DLE where some additional disk space can be allocated
This example assumes a volume group with two 200 GB disks on which one logical volume with two
mirrors has used up all of the extents. You want to increase the LUN sizes to 300 GB to expand the
logical volume. However, you created the volume group with a relatively small maximum VG size
(500 GB). When vgmodify tries to reconfigure the physical volumes, it is only able to increase the
total number of extents to 64000 because of the 500 GB limit on the VG size. The maximum number
of extents (64000) for the VG equals the maximum VG size (500 GB) divided by the extent size (8
MB).
1. Review current volume group and LUN attributes.
# vgdisplay –v vg1
--- Volume groups ---
VG Name /dev/vg1
...
PE Size (Mbytes) 8
Total PE 51196
Alloc PE 51196
Free PE 0
...
VG Version 2.1
VG Max Size 500g
VG Max Extents 64000
--- Logical volumes ---
LV Name /dev/vg1/lvol1
LV Status available/syncd
LV Size (Mbytes) 204784
Current LE 25598
Allocated PE 51196