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Re: Disk Capacity Limit

 
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Piotr Kirklewski
Super Advisor

Disk Capacity Limit

Hi there

I'm mirroring disks, and there is an error regarding disc capacity limit for vg03.
How to change the Disk Capacity Limit for volume group ?

Cheers
Jesus is the King
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Sandman!
Honored Contributor
Solution

Re: Disk Capacity Limit

Please post the exact error message you are getting.

~thanks
A. Clay Stephenson
Acclaimed Contributor

Re: Disk Capacity Limit

When a volume group is created there are severval values that are set and remain fixed thereafter. For example: max_pv's and maxPe's. Moreover, while you may have enough free extents in a volume group to allow a mirror, you may not have enough free pe's on separate PV's to conform to the allocation policy. Please post your exact error message.
If it ain't broke, I can fix that.
Piotr Kirklewski
Super Advisor

Re: Disk Capacity Limit

The error is:

At least one of the disks you have chousen is larger then the maximum size allowed by volume group vg03 (8676 Mbytes). These disks can still be used, but any capacity beyond the volume group limit will be wasted.
Jesus is the King
hpuxrox
Respected Contributor

Re: Disk Capacity Limit

Clay is correct. However, hitting the MAX_PV limit is the most common. The architect should always allow more that the default value within LVM. I usually go 64, although always take in to consideration the needs and future needs of the system.
A. Clay Stephenson
Acclaimed Contributor

Re: Disk Capacity Limit

It means exactly what it says. The max_pe value was set when the VG was created and can't be increased. When you create a VG, it's wise to anticipate the largest disk (or LUN) that you will ever wish to use and set the max_pe's and pe_seize accordingly. You have two choice. 1) Backup, Build the VG from scratch, Restore 2) Use the larger disk but be prepared to have a portion of it unaccessible. 3) Rather than adding 1 large disk add two smaller disks to the VG (OK that's 3 but who's counting?).
If it ain't broke, I can fix that.
hpuxrox
Respected Contributor

Re: Disk Capacity Limit

You posted before i could refresh, looks like you have reached MAX_PE.
James R. Ferguson
Acclaimed Contributor

Re: Disk Capacity Limit

Hi Peter:

> At least one of the disks you have chousen is larger then the maximum size allowed by volume group vg03 (8676 Mbytes). These disks can still be used, but any capacity beyond the volume group limit will be wasted.

This reflects that the LVM geometry is fixed at the time of volume group creation ('vgcrete'). That is, elements describing the geometry like 'max_pe' and 'pe_size' are fixed and cannot be changed.

Large physical disks may require larger values to be fully utilized. To circumvent this problem, backup your data; destroy the volume group ('vgexport', or 'vgremove'); and create it again ('vgcreate') specifying appropriate values for 'max_pe', 'pe_size' and perhaps 'max_pv' and 'max_lv'. See the manpages for 'vgcreate' for more information.

Regards!

...JRF...
James George_1
Trusted Contributor

Re: Disk Capacity Limit

Hi

As everybody has replied, this is the max_pe extends problem . Make it a practice to add the largest disk when u create the Volume groups.


Rgds / James
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hpuxrox
Respected Contributor

Re: Disk Capacity Limit

Also, keep in mind that there is 64k PE limit per volume group. So, with the default PE_SIZE 4M, you will have a 256M limit on the file system. I would recommend a PE size of atleast 16M and MAX PV of 64 for any SAN attached storage. There is very little performance impact for doing this.