topic Cannot create a volume group in Operating System - HP-UX

Cannot create a volume group

John Booth_1 — Thu, 04 Oct 2001 13:35:03 GMT

I am trying to create a volume group on a disk array. I have about 140G's of space that I need to make into a volume group. When I try to create the volume group this is the error I recieve:
vgcreate vgbpcsdb /dev/dsk/c3t0d0
Increased the number of physical extents per physical volume to 34109.
vgcreate: Volume group "/dev/vgbpcsdb" could not be created:
File too large

Any suggestions??

Thank you,
John

Re: Cannot create a volume group

Stefan Farrelly — Thu, 04 Oct 2001 13:39:04 GMT

140G at a PE size of 4 MB is just too many extents for the Vg. You need to increase the PE size up from 4 MB - possibly you will have to go up to 16 MB in order to be able to create the VG.

Re: Cannot create a volume group

James R. Ferguson — Thu, 04 Oct 2001 13:42:10 GMT

Hi John:

The LVM structures must fit into one physical disk extent. This is the "file too large" error. You can adjust your 'pe_size', 'max_pv', and 'max_lv' to accomodate this. See the man pages for 'vgcreate' for more details.

Regards!

...JRF...

Re: Cannot create a volume group

Sridhar Bhaskarla — Thu, 04 Oct 2001 13:42:31 GMT

You need to change the PE size to either 8 or 16MB. Use -s option while creating the volume group.

vgcreate -s 8 vgxx /dev/dsk/cxtydz

-Sri

Re: Cannot create a volume group

A. Clay Stephenson — Thu, 04 Oct 2001 13:45:16 GMT

Hi:

While the size of your VG is not too big, you need to increase the size of physical extents using the -s vgcreate argument from the default 4MB to perhaps 16 or 32MB. Remember the -s arg must be a power of two.

Regards, Clay

Re: Cannot create a volume group

Patrick Wallek — Thu, 04 Oct 2001 13:50:13 GMT

Here's a good document from the TKB on this subject. Doc ID KBRC00000716

vgcreate error: file too large
DocId: KBRC00000716

Updated: 3/23/01 7:43:00 AM

PROBLEM

When attempting to create a new volume group with vgcreate, an error occurs: file too large

CONFIGURATION

HP-UX 10.X, 11.X

RESOLUTION

Since the LVM data structures must fit into a single extent on the disk, the "file too large" error occurs when the extent size is smaller than the LVM data structures.

As disks continue to increase in size, there is not enough room in the header files to create a table large enough to track all the physical extents.

On the one hand, you can reduce the size of the LVM data structure by reducing the maximum number of logical volumes the volume group can contain (max_lv), or, the maximum number of physical volumes the volume group can contain (max_pv).

On the other hand, you can increase the size of the physical extents (pe_size) so that the LVM data structure will fit into a single extent.

# vgcreate -l (number of max logical volumes) -p (number of max physical volumes) -s (size in megabytes of physical extent) /dev/vg## /dev/dsk/c#t#d#

By default, these parameters are set to:
max_lv 255
max_pv 16
pe_size 4MB

Re: Cannot create a volume group

Wodisch — Fri, 05 Oct 2001 15:42:06 GMT

Hello John,

this question pops up quite often, and the answer is
always: Use bigger PEs, not more of them!
If you would "search" the forums, you would find a lot
of explanantions and recommendations (even from Bill
Hassel himself) to use bigger PEs. Since the defaults
were made back in time of HP-UX 9(!), when disks were
much smaller, they have never been increased (or call it
adpated to reality). But that does not tell you to stick
with them. When the first steam locomotives run, there
was a discussion, wether the human body would actually
survive the speed of more than 30km/h - do we still drive
only that fast today?
AFAIK is the maximum size for PEs 256MB/PE and that is
supported! So you may use it! So do it!
The drawbacks are slightly bigger LVs (they need to be
multiples of the PE-size) and sometimes slower a slower
re-mirroring after a "lvsplit" or break. Is that tolerable
for you?

Kind regards,
Wodisch

PS: I am still wondering why those great features of
todays UN*Xs (like HP-UX 11.*) are not used more often:
PEsize up to 256MB, POPS of up to 256MB/page - really
great and useful stuff! W.