Error with "vgcreate /dev/vg01 /dev/dsk/c12t1d3" statement

[cbozlagan]

Error with "vgcreate /dev/vg01 /dev/dsk/c12t1d3" statement

Error:
======
Warning: Max PE per PV for the volume group (65535) too small for this PV (76799).
Using only 65535 PEs from this physical volume.
Increased the number of physical extents per physical volume to 65535.
vgcreate: Volume group "/dev/vg01" could not be created:
VGRA for the disk is too big for the specified parameters. Increase the
extent size or decrease max_PVs/max_LVs and try again.


How can I increase the extent size or decrease max_PVs/max_LVs?

Thanks

[Pete Randall · Accepted solution]

Add the "-s pe_size" parameter to your vgcreate command in order to specify the size of the extents. See "man vgcreate".


Pete

[ASIFKHAN]

Hi cbozlagan,

As i have seen your problem i think u were either trying to use the number of PE's more than max. number of PE's per PV (per disk) i.e. 65535 while creating volume group by the following command:

#vgcreate -e 76799 /dev/vg01 /dev/dsk/c1t2d3 (wrong way)

I would recommend to use below command to set the limit of max number of PE's in a PV:
#vgcreate -e 65535 /dev/vg01 /dev/dsk/c1t2d3


or you were trying to use a disk of larger capacity than supported on your system.

Largest supported disk(PV) for a VG=
single PE size * max. number of PE's per PV.

eg.if PS size is 4MB & maximum number of PE per PV is 1016.Then

Largest supported disk(PV) in a VG =4*1016 =4064MB =approx 4GB disk(PV)

So it will be better to increase max number of PE's per PV by

#vgcreate -e 65535 /dev/vg01 /dev/dsk/c1t2d3


you can increase the extent size by using this command while creating volume group:
eg:if we want to set PE size as 8MB then

#vgcreate -s 8 /de/vg01 /dev/dsk/c1t2d3

To decrease max_PVs :But first know that number of max_PVs per VG is 255 and default is 16.

suppose u want max of 10 PV's per VG then
#vgcreate -p 10 /dev/vg01 /dev/dsk/c1t2d3

To decrease max_LVs :but first know that number of max_LVs per VG is 255 and default is also 255.

suppose u want max of 220 LV's per VG then
#vgcreate -l 220 /dev/vg01 /dev/dsk/c1t2d3

Hope it will help u:
plz reply
Mohd. Asif Khan
(INDIA)

[ASIFKHAN]

PLZ TELL ME THE SIZE OF YOUR PV.
SO THAT I CAN SOLVE YOUR PROBLEM EASILY.

IF IT IS MORE THAN 146 GB
THEN USE THIS COMMAND:

#vgcreate -s 8 /dev/vg00 /dev/dsk/c1t2d3

here -s sets the size of PE to 8MB.

Thanks
Mohd. Asif Khan

[Andrew Jendricks]

Hello,

There are really two things happening here.

Note that the PE per PV message is merely a warning, not an error. What it's telling you is that if you proceed with the default setting for Physical Extent (PE) size (4mb) you will only be utilizing 256GB of this 300 GB lun, which you can do, if you don't mind wasting 44gb. This is because LVM only allows you to map 65535 PEs for each physical volume (PV).

So, if you use the -s option for the vgcreate command along with the value of 8 (8mb) then you will only have 38399 because you will have set your extent size to 8mb.

Even with this option setting, you may still run into the second part of the message, which is an error, and will not allow you to proceed.

The second part has to do with the extent mapping table which is stored in the VGRA, or Volume Group Reserve Area. The VGRA, along with the PVRA and some other meta data objects, all must fit in an area set aside on each physical volume in the group. The space for all of these reserved areas is the size of one physical extent. By increasing the extent size you not only double (in this case) the amount of space for this reserve area, but you also cut in half the the number of extents which must be mapped, essentially halving the size of the table.

However this may still not be enough to eliminate the "VGRA too big..." part of the error.

The reason is that even though you may only be creating the volume group with one disk (lun) at this moment, LVM is creating the mapping table for the maximum allowable number of disks (PV), or the MAX_PV variable, which defaults to 16. It is possible, if not probable, that quantity 16 300gb luns would create a extent mapping table too large to fit in the first extent, even with a larger extent size of 8mb, and a smaller extent count per PV of 38399.

To change the MAX_PV parameter, use the -p option. You can tinker with it, perhaps starting with 10 or 12 as a value, and going lower as needed, until you find a value which works.

The syntax would be:

#vgcreate -s 8 -p 12 /dev/vg01 /dev/dsk/c12t1d3

Good luck.