topic LVM Question: lvcreate command in Operating System - HP-UX

LVM Question: lvcreate command

LG Porter — Fri, 03 May 2002 01:03:49 GMT

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?

Re: LVM Question: lvcreate command

Victor_5 — Fri, 03 May 2002 01:11:48 GMT

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.

Re: LVM Question: lvcreate command

S.K. Chan — Fri, 03 May 2002 01:12:32 GMT

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

Re: LVM Question: lvcreate command

Victor_5 — Fri, 03 May 2002 01:16:39 GMT

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

Re: LVM Question: lvcreate command

Tom Geudens — Fri, 03 May 2002 03:18:27 GMT

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

Re: LVM Question: lvcreate command

Roger Baptiste — Fri, 03 May 2002 03:49:51 GMT

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

Re: LVM Question: lvcreate command

Bill Hassell — Fri, 03 May 2002 10:40:31 GMT

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.