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

75
LV Size (Mbytes) 409064
Current LE 51133
Allocated PE 51133
Used PV 2
--- Physical volumes ---
PV Name /dev/disk/disk46
PV Status available
Total PE 25533
Free PE 0
...
PV Name /dev/disk/disk47
PV Status available
Total PE 38333
Free PE 12733
4. Run a storage utility to contract the second PV from 400 GB to 300 GB.
5. Verify that the LUN is smaller.
# diskinfo /dev/rdisk/disk47
SCSI describe of /dev/rdisk/disk47:
…
size: 314572800 Kbytes
Online reprovisioning to decrease the maximum volume group size
In this example, you know that the maximum VG size of 256 TB is more than what is needed for this
volume group in the future. You want to decrease the maximum VG size to 64 TB.
1. Run vgmodify in review mode to verify you can decrease the maximum VG size below the
current VG size of 510928 MB (63866 extents from the Total PE value from the previous
example multiplied by the 8 MB extent size).
# vgmodify -r -a -S 500m vg1
vgmodify: Error: Cannot reconfigure the volume group "/dev/vg1" to
the requested maximum volume group size 500 MB.
The maximum volume group size can be decreased
to a minimum of 510928 MB.
Physical volume "/dev/disk/disk46" was not changed.
vgmodify: Error: Cannot reconfigure the volume group "/dev/vg1" to
the requested maximum volume group size 500 MB.
The maximum volume group size can be decreased
to a minimum of 510928 MB.
Physical volume "/dev/disk/disk47" was not changed.
The desired (smaller) maximum VG size is too small.
2. Run vgmodify in review mode to verify you can decrease the maximum VG size from 256
TB to 64 TB.
# vgmodify -r -a -S 64t vg1
Physical volume "/dev/disk/disk46" requires reconfiguration to be
provisioned to the requested maximum volume group size 67108864 MB.
Current number of extents: 25533
Number of extents after reconfiguration: 25582
Physical volume "/dev/disk/disk46" was not changed.
Physical volume "/dev/disk/disk47" requires reconfiguration to be
provisioned to the requested maximum volume group size 67108864 MB.
Current number of extents: 38333
Number of extents after reconfiguration: 38382
Physical volume "/dev/disk/disk47" was not changed.
49 extents will be added to each PV.