Creating a logical volume from shell?

[rmueller58]

I am working on adding multiple logical volumes, I can use SAM however I'd prefer to create them from the shell.

I've got multiple volume groups with available space, I have to setup informix databases using RAW space,

how can I create the logical volume below
/dev/vg## without having to go into SAM?

[curt larson_1]

you would use the lvcreate command
see the lvcreate man page for possible options that you'll need to use

[rmueller58]

Curt,
it is pretty cryptic.

From the man page I can see HOW to create one, but on how to point to the Volume Group.. If it is created by default in the correct VG will it work OK?

[Jeff Schussele · Accepted solution]

Hi rex,

Use the following

lvcreate -L XXXXX -n lv_name /dev/vg_name

where XXXXX=size in MB. If you're going to want a mirror then add -m 1 If you want it striped then add -i x -I YYY where x=number of disks in the stripe (stripe count) & YYY=stripe size in KB (must be power of 2)

HTH,
Jeff

[rmueller58]

Thanks I'll give it a shot..

[Marc Smith]

Maybe this is better:

lvcreate -L -n

IIRC, you can leave out the -n switch and it'll create it with a lvol## format.

Then you can check it with:

lvdisplay -v /dev//

If you're not creating raw volumes, you need to do this:

newfs -F vxfs /dev//

Then add it to you fstab and mount it.

[Jeff Schussele]

Since you're wanting raw volumes then you can skip the next step of filesystem creation.
You just start using /dev/vg_name/lv_name
But you should consider putting *commented* entries in the /etc/fstab as a reminder or a placeholder if you will for those LVs you've created in those VGs because they'll never show up in a bdf output & can become forgotten over time.

My 2 cents,
Jeff

[Jeff Schussele]

Marc's correct - you don't *need* the -n lv_name. It will give you the next lvolX value by default.
BUT I hate that. I want my lv_name to tell me just what the heck that LV's for. I want it to have meaning - not just another number. Just my preference.

Rgds,
Jeff

[Marc Smith]

Wow...I don't know how I missed where you said you wanted raw volumes...Oh well, It's Friday. ;)

[rmueller58]

Ok,

I am starting to get confused so let me run this past you all.

for example if I use:
lvcreate -L 1048576 -n plvdbs /dev/vg02

It will create the RAW logical called plvdbs since I am not creating a VXFS?

[Marc Smith]

Yep. It's the newfs command that creates the filesystem. You will have a raw volume as long as you don't run newfs.

Sorry for the confusion.

[rmueller58]

cool..

We are heading in an upgrade and need to parallel 22 informix spaces.. I will script it and be done with it..

[Patrick Wallek]

What size are you looking for?

The '-L 1048576' will create a 1,048,576 MB = 1,024 GB = 1 TB Volume. Do you want 1 TB?

[rmueller58]

no.. 1 Gb. or 512m for the most of them

[Patrick Wallek]

You must remember then that you specify the size with the -L option in MB. So if you want 1 GB (1,024 MB) then it is '-L 1024' and if you want 512 MB then it is '-L 512'.

[rmueller58]

Thanks Patrick for clarifying the size..
And Mark and Jeff for the assist..