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Logical Volume & Volume Groups

Jeff Hagstrom
Regular Advisor

Logical Volume & Volume Groups

On one box there are only 3 logical volumes setup and 20 volume groups, on the other box there are 9 logical volumes setup and 20 volume groups. Is there any particular way the logical volumes should be setup? Or is it ok to have 1 for each volume group?
7 REPLIES
harry d brown jr
Honored Contributor

Re: Logical Volume & Volume Groups

Jeff,

I think you mean you have 3 Volume groups with 20 logical volumes spread between the volume groups for the first box.

For the second box I think you mean you have 9 volume groups with 20 logical logical volumes.

A logical volume can also be called a filesystem, when it's a mounted filesystem and not a raw logical volume that's used for some databases.

Usually I group Volume groups by "business units/process", and then create the necessary logical volumes (filesystems) under each as necessary.

live free or die
harry
Live Free or Die
Robert-Jan Goossens
Honored Contributor

Re: Logical Volume & Volume Groups

Hi Jeff,

Think you mean 3 VG's and 20 LV's.

I try to use following.

VG00 OS
VG01 aplication's
VG02 DATA

Kind regards,

Robert-Jan.
John Poff
Honored Contributor

Re: Logical Volume & Volume Groups

Hi,

The usual answer - it depends, usually on your application. If you have an application like a big database, it might be happier having lots of logical volumes. We setup our Oracle databases that way, especially because it helps us with backups - more LVs mean more streams for OmniBack. On the other hand, some applications just want a large, single filesystem / logical volume.

Did you mean 3 volume groups and 20 logical volumes, and 9 volume groups and 20 logical volumes? Otherwise you would have volume groups without any logical volumes.

JP
MANOJ SRIVASTAVA
Honored Contributor

Re: Logical Volume & Volume Groups

Hi Jeff


It all depends on

1. Ease of setup
2. Ease of backups.
3. High I/O areas interms of I/o bcoz of database.
4. Future expansion.


genrally I would consider all the above in the order 3 4 1 2 also considereing not to have more than 3-4 Phyiscal volumes per volume group.


Manoj Srivastava

James R. Ferguson
Acclaimed Contributor

Re: Logical Volume & Volume Groups

Hi Jeff:

A couple of things come to mind when setting up volume groups and their associated logical volumes.

First, at present, it is not possible to alter LVM geometry like 'pe_size', 'max_pe', 'max_pv' and 'max_lv' *except* at volume group creation. Poor planning can mean that you will end up recreating your volume group and reloading your data in some way, shape or fashion.

Next, your kernel limits you to 'maxvgs' volume groups. By default this is <10> although it can be increased. Each volume group on your system requires about 4-8KB of lockable physical memory.

Regards!

...JRF...
Vicente Sanchez_3
Respected Contributor

Re: Logical Volume & Volume Groups

Hi Jeff,

It depends on:

The number of the number of disks.
The performance level.
The number of applications.
The security level you want to implement.

Normally few volume groups and several logical volumes per VG.

Regards, Vicente.
James R. Ferguson
Acclaimed Contributor

Re: Logical Volume & Volume Groups

Hi (again) Jeff:

You'll make your life easier if you always reserve vg00 for the OS *only*. This makes upgrades, cold-installs, and Ignite recovery much simpler than working with a VG00 that contains logical volumes that are application-specific.

Regards!

...JRF...