topic LVM ISSUE in Operating System - HP-UX

LVM ISSUE

subrata biswal — Sun, 20 Mar 2011 16:23:05 GMT

I have 3 hard disk and i have to create 3 physical volume and one volume group and one logical volume.each hard disk size is 8 GB.
my volume group size will be 24 and logical volume group will be same 24GB.

How i will configure ?can any one tell me the solution?

Re: LVM ISSUE

Ismail Azad — Sun, 20 Mar 2011 19:09:01 GMT

Hi subrata,

On 11.23 > /dev/rdsk/cxtxdx
On 11.31 > /dev/rdisk/diskx

Assuming 11.31, as you have not mentioned uname -a

Let's say PV1 :-/dev/rdisk/disk1
PV2:- /dev/rdisk/disk2
PV3:- /dev/rdisk/disk3
These are random names.

Note :- execute 1)ioscan -funNC disk... These are available disks.

2)strings /etc/lvmtab... Used by LVM. Hence, find the disk in command 1 that is not_there in command 2. You can create a PV on this disk as long as it is not a DVD/CD etc...

pvcreate -f /dev/rdisk/disk1
pvcreate -f /dev/rdisk/disk2
pvcreate -f /dev/rdisk/disk3
mkdir /dev/vgexample
Execute ls -l /dev/*/group... See the_used minor numbers
Execute mknod /dev/vgexample/group c 64 0x030000.... First 2 characters for the VG... Last 4 are always 0 for the group control file.
vgcreate /dev/vgexample /dev/disk/disk1 /dev/disk/disk2 /dev/disk/disk3

This will create a pool of space of three 8GB disks as a 24GB volume group.

Now, execute lvcreate -L 240000 -n example vgexample

This creates an L.V with device files /dev/vgexample/rexample and /dev/vgexample/example.

Dont forget to assign points.

Regards
Ismail Azad

Re: LVM ISSUE

James R. Ferguson — Sun, 20 Mar 2011 20:10:04 GMT

Subrata:

> How i will configure ?can any one tell me the solution?

And your profile shows "Certification: HPCSA" ?!?! That must mean something different than what I think it does.

I suggest that you read an administration guide appropriate for the release that you don' t mention as one first step in your education.

...JRF...

Re: LVM ISSUE

subrata biswal — Mon, 21 Mar 2011 01:28:08 GMT

As per your reply I am already knowing the step. But in interview some body told that is wrong way that why i am putting in forum.not for my knowledge?
And one thing what Ismail Azad mention in the result same thing i told?

For that reason i put in the forum.

THanks

Re: LVM ISSUE

Patrick Wallek — Mon, 21 Mar 2011 01:36:09 GMT

>>But in interview some body told that is wrong way

What did they say was wrong?

What exact steps did you give as your answer?

Re: LVM ISSUE

subrata biswal — Mon, 21 Mar 2011 01:51:02 GMT

MY answer is

pvcreate -f /dev/rdisk/disk1
pvcreate -f /dev/rdisk/disk2
pvcreate -f /dev/rdisk/disk3

mkdir /dev/vg00
mknod /dev/vg00/group c 64 0*000000
vgcreate /dev/vg00 /dev/dsk/disk1 /dev/dsk/disk2 /dev/dsk/disk3

lvcreate -L size of the logical volume
make a directory
mount the directory.

Re: LVM ISSUE

Kapil Jha — Mon, 21 Mar 2011 01:51:38 GMT

I understand if interviewer is asking something and you start to answer most of the time he would expect something else apart from plain answer.

You missed the part where you could have told the maximum PV allowed, PE size various other options which are general but necessary to decide a LVM configuration.

One thing where interviewer seems to be wrong is he gave very small disk size 8G, it can be tricky if he says he want a FS which is bigger than 2G, or what a file system for large file options.

You were right when you answered but still you could have added other point to impress the interviewer.

Good Luck!!

BR,
Kapil+

Re: LVM ISSUE

subrata biswal — Mon, 21 Mar 2011 01:56:09 GMT

thanks for reply and giving the suggestion .
But i am working in L1 level in a govt organisation.How much i know i gave the answer.

He did not ask about PE and pv also.

thanks

Re: LVM ISSUE

Ismail Azad — Mon, 21 Mar 2011 05:24:46 GMT

Hi subrata,

> Subrata
will be 24 and logical volume group will be same 24GB.

Well if that's the way he asked the question, the terminology_is_wrong as your post mentions "logical volume group" and it's minutely possible that he wanted you to point it out.

> As per your reply I am already knowing the step. But in interview some body told that is wrong way that why i am putting in forum.not for my knowledge?

Perhaps there is more to the question you are leaving out? Probably has something to do with the planning of the size of an LV and now that single LV can only be used for one "specific" purpose unless you have F/S swap . Probably he is trying to ask you to find a fault in the design of the scenario he has mentioned and there could_be_many.

Regards
Ismail Azad

Re: LVM ISSUE

Sajjad Sahir — Mon, 21 Mar 2011 06:35:04 GMT

Dear Subratha

the following lvm verison is coming with
hp-ux 11iv3 and u didn't ask him
what is the lvm version
then only u can anser him
because we are using in 11iv3 the following
command to create the volume group

LVM 2.x Volume Group coming with hp-ux 11iv3

# vgcreate /dev/ /dev/disk/disk# ...

and LVM 1.0 Volume Group previous version

using the command
#vgcreate /dev/ /dev/disk/c#t#d#

thanks and regards

sajjad Sahir

Re: LVM ISSUE

subrata biswal — Mon, 21 Mar 2011 08:37:32 GMT

ok for all off you who gave the suggestion to me.
He asked only general lvm not in 11iv3 or 11iv2.

Re: LVM ISSUE

James R. Ferguson — Mon, 21 Mar 2011 13:05:51 GMT

Hi (again):

> He asked only general lvm not in 11iv3 or 11iv2.

In my opinion, you could easily have asked the interviewer which version was the basis for the question; _OR_ you could have answered with additional comments that on 11.31, doing a 'mkdir' and 'mknod' of the VG directory and group are optional and if you elect to do it manually, the minor number changes from 64 to 128 if you specify a version 2.x volume group.

If giving too many details would be a distraction, I would at least have said something to the effect that beginning with 11.31, there are some minor differences and/or shortcuts. This gives the interviewer a chance to further probe you and should pique his/her interest in your skills.

Regards!

...JRF...

Re: LVM ISSUE

P Arumugavel — Mon, 21 Mar 2011 16:40:44 GMT

hi subrata,

Please keep in mind. Interviewer always test how confidence you have on what you know, not how much you know. If you feel your reply is right, you should have asked him I am sure with my points and tell me where if i am wrong. This will make them more interest to take you ahead.

Do not give typical answer, show your skill in giving the answer in the way.

Rgds...