Originally posted by: pandith

Hi Friends-

We know that the Max PP size in a Normal VG and Big VG is 1 GB and in case of scalable VG it is 128 G.

My Questions:

1) What is the min PP size allowed for Normal VG, Big VG and Scalable VG?

2) Why is the max PP Size in Normal and Big VG is 1 G and 128 G in scalable VG?
Thanks in advance
Pandith

Originally posted by: l2abe

For normal and big VG the PP size depends upon the disk size. The LVM design, before Scalable VG, was in fact allowing a maximum allocation of 1016 PP per Physical Volume with a minimum PP Size of 1Mb.
What does it mean? That means that if you use a PP size of 1Mb you cannot allocate more than 1Mb * 1016 (a little less than 1Gb) per physical volume.
However a VG enhancement has been to use what is called the "t" factor flag for chvg command. Using this flag infact you can half the maximum number of disks per VG but doubling the number of PP per disk. For example using a "-t 2" for a bigVG the maximum number of PVs allowed in the VG will 64 (instead of 128) but then you can allocate up to 2032 PP per disks.
The minimum PP size of 1Mb is for SVG as well while, as you said the maximum is 128GB! The reason? Simply a design enhancement, SVG is more flexible and allows to allocate bigger storage space, you are no more limited to 1016 PP per Physical Volume, independently on the number of Physical Volumes used you can arrive to allocate up to 2097152 PP...choose the PPsize you like more.