Maximum PE size in a VG ?

[Bruno Köhle]

What is the total PE in a VG ?
Is there any performance impact in calculation PE size,max PE per PV or numbers of PV in a VG ?

[Printaporn_1]

Hi
From vgcreate manpage
-e max_pe Set the maximum number of physical extents
that can be allocated from any of the
physical volumes in the volume group. The
default value for max_pe is 1016. However,
if the size of any physical volume exceeds
1016 times the pe_size, the default value for
max_pe is adjusted to match the physical
volume size. The maximum number of physical
extents can be a value in the range 1 to
65535.


-s pe_size Sets the number of megabytes in each physical
extent, where pe_size is expressed in units
of megabytes (MB) in the range 1 to 256.
pe_size must be equal to a power of 2 (1, 2,
4, 8, etc.). The default value for pe_size
is 4 (four megabytes).

[Bruno Köhle]

Is there a limitation on maximun PE in the whole volume group ?

[Armin Feller]

Hi,

yes there is a limit. Please have a look in the man page of vgcreate:

...

-s pe_size

Sets the number of megabytes in each physical extent, where pe_size is expressed in units of megabytes (MB) in the range 1 to 256.
pe_size must be equal to a power of 2 (1, 2, 4, 8, etc.). The default value for pe_size is 4 (four megabytes).

Regads ...
Armin

[Armin Feller]

If you need to know how many physical disks you can add, see also in the man page vgcreate:


-e max_pe

Set the maximum number of physical extents that can be allocated from any of the physical volumes in the volume group. The default value for max_pe is 1016. However, if the size of any physical volume exceeds 1016 times the pe_size, the default value for max_pe is adjusted to match the physical
volume size. The maximum number of physical extents can be a value in the range 1 to 65535.


Regards ...
Armin

[T G Manikandan]

Like the default max PE is 1016 and will be adjusted to the size of Physical volume added in the volume group during the volume group creation time.

If you add a disk of size 18GB in the volume group whose max PE would be 4340.
(PE adjusted to the size of the physical volume).

Then if you try to extend the VG with a hard disk of 36 GB size you will be able to use only 18GB of that hard disk as the MAXPE was allocated during the VG creation time.

REvert