VG with 300 GB size (creation error)

[Hasan_9]

Hi,
I plan to create a big volume group about 300 GB size. vgcreate reports the following error. What should I do? Is there a limitation in size of VG?
Please Advice.
Hasan


# vgcreate /dev/vg_rac /dev/dsk/c9t0d1
Warning: Max_PE_per_PV for the volume group (65535) too small for this PV (127999).
Using only 65535 PEs from this physical volume.
Increased the number of physical extents per physical volume to 65535.
vgcreate: Volume group "/dev/vg_rac" 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.

[A. Clay Stephenson · Accepted solution]

The maximum number of PE's is 64K. The default PE size is 4MB. You need to increase the PE size to 8MB or 16MB. There is no performance impact from doing this; it's only bookkeeping.

[Pete Randall]

You need to specify the pe_size parameter. The default PE size is too small to contain the VGRA. Add the "-s pe_size" parameter to your vgcreate and make the pe_size something like 32 or 64.


Pete

[DCE]

Hasan,

If you are not familar with all of the command line options for vg creation, You can also use SAM to create the VG. The screens within SAM will allow you to customize the VG configuration to allow you to use all of the disk.

Once you have created the VG, you can use command line to extend it.

[Devender Khatana]

Hi,

Allthough there are some limits in LVM but still your case do not fall out of them. There is limitation of using small PE_Size and maxPVs/Max LVs in a VG.

Limits attached for you reference.

HTH,
Devender

[Steven E. Protter]

Shalom,

You can also create the volume group with less maximum disks. This distributes the 65535 PE's over less disks.

just add this to the create command.

-p 10

Make sure 10 disks is enough for a long time, because it can't be changed on the fly.

The default is 255, which in general is too big and leads to this issue.

Good Luck,

Shmuel

[dictum9]

I am running into the same issue with identical error, and doing research, it looks like max_PV by default is 16, not 255. This is from the man page on Itanium 11.23.


Therefore, giving the option of "-s 32" to vgcreate makes more sense.

[dictum9]

Still running into issues:


vgcreate -s 64 /dev/vg01 /dev/dsk/c6t0d0

vgextend: Warning: Max_PE_per_PV for the volume group (1199) too small for this PV (1359).
Using only 1199 PEs from this physical volume.


Should I go to "-s 128" or adjust Max_PE_per_PV with the "-e" switch?

[Brian T. Borders_1]

There are usually two main errors that can occur when creating a VG with large PV.

1. The pe_size needs to be large enough to hold the VGDA. The fix for this is to increase the PE size.
2. The max_pe needs to be large enough to hold all the pe's created by the pe_size. This can be done two ways, use the maximum value of 65535 or divide the disk size by the pe_size.

A 360GB disk equals 368640MB.
Divide 368640MB by the pe size of 4MB = 92160 pe's
Divide 368640MB by the pe size of 8MB = 46080 pe's
So for a 360GB PV the requires a minimum pe_size of 8MB (-s 8) and minimum max_pe of 46080 (-e 47000)

facettst(LOCAL:root)/root # vgdisplay vgdb02
--- Volume groups ---
VG Name /dev/vgdb02
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 14
Open LV 14
Max PV 40
Cur PV 1
Act PV 1
Max PE per PV 21875
VGDA 2
PE Size (Mbytes) 16
Total PE 21861
Alloc PE 21861
Free PE 0
Total PVG 1
Total Spare PVs 0
Total Spare PVs in use 0

facettst(LOCAL:root)/root #

facettst(LOCAL:root)/root # diskinfo /dev/rdsk/c8t0d6
SCSI describe of /dev/rdsk/c8t0d6:
vendor: HP
product id: A5277A
type: direct access
size: 358232000 Kbytes
bytes per sector: 512
facettst(LOCAL:root)/root #


vgcreate from man page - 11.00
-A autobackup [default=y n]
Set automatic backup for this invocation of this command

-e max_pe [default=1016, Range 1 - 65535]
Set the maximum number of physical extents that can be allocated from any of the physical volumes in the volume group. 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.

-f Force vg creation
This option will force a volume group to be created with a physical volume which has alternate block(s) already allocated, (i.e. this physical volume was not initialized using pvcreate -f.) This option should be used with extreme caution.

-g pvg_name
Create a new physical volume group with the name pvg_name. All physical volumes specified in the pv_path parameter become a member of the newly created physical volume group. The physical volume group information is stored in an ASCII file,
/etc/lvmpvg.

-l max_lv [default=255]
Set the maximum number of logical volumes that the volume group is allowed to contain.

-p max_pv [default=16]
Set the maximum number of physical volumes that the volume group is allowed to contain.

-s pe_size [default=4, Range 1 - 256]
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.

-x extensibility [defaut=y]
Set the allocation permission for adding physical extents on the physical volumes specified by the pv_path parameter.