volume group and volume extend

[Chung]

Hi Expert,

I have question about volume group and volume extend. Exist lvdb2 volume around 150GB, and I check the "Max PE per PV" is 38399 and the "Total PE" is 38394. If I create large LUN 400GB and extend the volume, how much maximum sixe can I extend it? Many thanks.


Chung



VG Name /dev/vgdbprd
VG Write Access read/write
VG Status available, exclusive
Max LV 255
Cur LV 1
Open LV 1
Max PV 8
Cur PV 1
Act PV 1
Max PE per PV 38399
VGDA 2
PE Size (Mbytes) 4
Total PE 38394
Alloc PE 38392
Free PE 2
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vgdbprd/lvdb2
LV Status available/syncd
LV Size (Mbytes) 153568
Current LE 38392
Allocated PE 38392
Used PV 1


--- Physical volumes ---
PV Name /dev/dsk/c6t0d3
PV Name /dev/dsk/c4t0d3 Alternate Link
PV Status available
Total PE 38394
Free PE 2
Autoswitch On

[Robert-Jan Goossens]

If you are going to add a lun to this volume group, the max size of the attached lun will be tied to the MAX PE X PE size

38399 X 4 = 153596 about 150 GB.

In other words, you can not use the full size of your new 400 GB lun. In order to access the full size you will need to recreate your volume group with a larger MAX PE size.

Robert-Jan

[Devender Khatana]

Hi,

Apart from Max_PE_PER_PV, the PE_Size is only 4MB so it will alllow only MAX_PE_PER_PV*PE_Size (4*38399=153596MB) of space to be used on one Physical volume in this VG. So from the LUN of 400GB you can only use 150GB, for making effective use of the space split the LUN in three equal size LUNs or create another VG, but in other VG volume extend can not be done so probably, splitting LUN is the only option apart from recreating VG with new parameters.

HTH,
Devender

[Pete Randall]

Because it only allows 38399 PEs per volume, you would only be able to extend it another 150GB. You could of course, create several smaller LUNs of 150GB each and extend it onto each of them, up to 8 in total.


Pete