LVM Question: lvcreate command

[LG Porter]

After extending a existing volume (vg01) with several new physical disks (c2t1d0, c3t0d0), I would like to create a logical volume to one of the new disk so that the file system will use only that disk. Using the lvcreate command, what is the correct syntax to create a logical volume to a specific disk?

[Victor_5]

The syntax is
lvcreate -L size -n lv_name vg_name

man lvcreate for more.

Since you have a couple of pv in your vg01, pv, lv and vg are all from logical point, I don't think you can do it.

[S.K. Chan · Accepted solution]

First you would create your LV without specifying the size. Then you would lvextend it with the size you wanted to the PV(disk) that you want it to reside.
EX:

# lvcreate -n lvol4 /dev/vg01
# lvextend -L 800 /dev/vg01/lvol4 /dev/dsk/c2t1d0

Check it afterwards ..

# lvdisplay -v /dev/vg01/lvol4 | more
# pvdisplay -v /dev/dsk/c2t1d0

[Victor_5]

I think S.K. Chan is correct, pls ignore my first post, sorry for about it.

[Tom Geudens]

Hi,
As an extra "add-on"
If some (part of) the logical volume doesn't end up where you want it, use pvmove to replace it. It's slow, but it works ONLINE. I consider it as one of the best LVM tools around.

Regards,
Tom

[Roger Baptiste]

To add to SK's post, the size for L would be in Megabytes.

Here is a LVM quick reference link:
http://us-support2.external.hp.com/cki/bin/doc.pl/sid=51ed1c020f23f4057b/screen=ckiDisplayDocument?docId=200000058994424

cheers
-raj

[Bill Hassell]

Create the lvol the same size as the disk. However, to force the lvol to a specific disk, use lvcreate with no length option. This creates a zero-length which you can extend using lvextend. lvextend can specify exactly which disk to use for the lvol.

Before you extend the lvol, use vgdisplay -v to determine the number of free extents on the desired disk. Then use lvextend -l free-extent-num /dev/vgXX/lvolYY /dev/dsk/WhatEver and recheck with vgdisplay. Once allocation is correct, then you can create the filesystem and mount the lvol.