[nflug] Here is something I should know, but I've never tried it in a production environment, so...

Richard Hubbard rhubby at yahoo.com
Tue Jun 24 11:39:21 EDT 2008


Thanks!

Can I change an existing partition to use LVM without losing data?


 <span style="font-family:comic sans ms;">Richard Hubbard </span>
ATTO Technology Inc



----- Original Message ----
From: David J. Andruczyk <djandruczyk at yahoo.com>
To: nflug at nflug.org
Sent: Monday, June 23, 2008 9:08:25 PM
Subject: Re: [nflug] Here is something I should know, but I've never tried it in a production environment, so...


Quick LVM primer:

using LVM on partitions:

fdisk drive, set aside apartition and set the partition type to 8e
pvcreate /dev/sdax
vgcreate  VolGRoupName /dev/sdax
lvcreate -L 10G -n LVname /dev/mapper/VolGroupName
mkfs -t ext3 -j /dev/mapper/VolGRoupName-LVname

It's also possible to use LVM ontop of a full device (in that case,  just use pvcreate /dev/sda),  partitions are better however as you can see if a disk has LVM on it, via using fdisk.

i.e. for me:
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          13      104391   83  Linux
/dev/sda2              14       30401   244091610   8e  Linux LVM

There are more advanced methods like using multiple disks per volume group, striping, etc...
It gets interesting when u get to play with a Sun Thumper (X4500), with 48 1 TB disks and you want to slice and dice the disks with SW raid and LVM.


 -- David J. Andruczyk



----- Original Message ----
From: Richard Hubbard <rhubby at yahoo.com>
To: nflug at nflug.org
Sent: Monday, June 23, 2008 7:02:59 PM
Subject: Re: [nflug] Here is something I should know, but I've never tried it in a production environment, so...


Not denying any advantages.

I'm just pretty old school sometimes.
// In other words, I haven't learned how to do LVM yet!

 <span style="font-family:comic sans ms;">Richard Hubbard </span>
ATTO Technology Inc



----- Original Message ----
From: David J. Andruczyk <djandruczyk at yahoo.com>
To: nflug at nflug.org
Sent: Monday, June 23, 2008 6:25:47 PM
Subject: Re: [nflug] Here is something I should know, but I've never tried it in a production environment, so...




 LVM has many advantages. i.e. when your raid card decides to present the devices in an alternate order, or you power up with a USB stick plugged in and that becomes /dev/sda, or your new box has a SATA device in it and hte kernel decides that's /dev/sda,  you'll wish you used LVM, or label based mounts.



-- David J. Andruczyk



----- Original Message ----
From: Richard Hubbard <rhubby at yahoo.com>
To: nflug at nflug.org
Sent: Monday, June 23, 2008 3:59:17 PM
Subject: Re: [nflug] Here is something I should know, but I've never tried it in a production environment, so...


Good old fashioned partition mounting (We don't need no stinkin' LVM!). The raid is hardware through the megaraid card, so as long as the flash remembers it's stuff, I shouldn't have a problem.

The raid partition is 3 virtual machines, 2 running, and the rest of the machine is pretty plain jane, with VMWare server installed.  One of the vm's is huge, though.(250 gb), so it would be much nicer if I didn't have to rebuild it.

I checked with a couple of people here, and they seem to be of the opinion that it should work.

Cross your fingers!

 <span style="font-family:comic sans ms;">Richard Hubbard </span>
ATTO Technology Inc



----- Original Message ----
From: Darin Perusich <Darin.Perusich at cognigencorp.com>
To: nflug at nflug.org
Sent: Monday, June 23, 2008 3:25:01 PM
Subject: Re: [nflug] Here is something I should know, but I've never tried it in a production environment, so...

I can't think of any reason why it shouldn't work but without knowing 
how everything is setup, LVM, raid, etc, it's only an informed guess. 
I'd make sure you have a full level 0 backup before you start playing 
around with this, just in case.

Richard Hubbard wrote:
> I have one older, slower server with CENT OS 5.1 on it.  So far, so good.
> 
> I want to move it over to another, newer, physical box.  No problem.
> 
> Problem: I have a drive array set up on the old box using an LSI 
> magaraid 6 SATA card.
> 
> Could I just take the physical drives out of the old box, put them into 
> the new box, complete with the Megaraid card, and have the CENT OS 
> recognize all the different hardware?
> 
> // I'm guessing "yes", but I'm worried about the drive array.  That has 
> the important data. The boot drive is a pretty generic setup and can be 
> remade in minutes.  The raid array would take a few days to rebuild.
>  
> Richard Hubbard
> ATTO Technology Inc
> 
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> nflug mailing list
> nflug at nflug.org
> http://www.nflug.org/mailman/listinfo/nflug

-- 
Darin Perusich
Unix Systems Administrator
Cognigen Corporation
395 Youngs Rd.
Williamsville, NY 14221
Phone: 716-633-3463
Email: darinper at cognigencorp.com
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