[CentOS] How to add a HD to a LVM

[Charlie Brune]

On 05/08/2011 09:37 AM, Todd Cary wrote:
> On 5/8/2011 12:03 AM, Ken Smith wrote:
>> Todd Cary wrote:
>>> I have connected a HD that was a prior system drive (Centos 4.8)
>>> and I am not sure of the command line procedures to find out if
>>> it is recognized (I believe it is since it present in the GUI),
>>> delete all data on it and finally add it to the LVM.
>>>
>>> I would like to use it as a backup data drive.
>>>
>>> Todd
>>>
>>>
>> This is an excellent tutorial on LVM.
>>
>> http://tldp.org/HOWTO/LVM-HOWTO/
>>
>> Are you planning to join it to an existing Volume Group and then create
>> a LV on it for backup? My preference would be to keep things simple and
>> to aid recovery in the future, maybe just format the disk ext3 for
>> backup. Then it is easy to plug into another box for recovery. But, I'm
>> just guessing how you plan to use it.
>>
>> Ken
>>
> Ken -
>
> Thank you for your response.  What you suggested is exactly what
> I would like to do: have an extra, stand alone, drive for
> backup.  However, when I do
>
> fdisk -l
>
> I get the output below which has me concerned.  As a "Sunday
> afternoon" user of Centos, I am not 100% sure of my
> interpretation - that is - the drive is already been joined as
> part of the LVM even though all I did was to plug it in as a slave.
>
> My installation of Centos 5.5 is new and I do not remember
> specifying LVM (though that is what I had with my 4.8 system).
> The /dev/hdc (250 GB) is the new system drive.  The /dev/hdd is
> the old Centos 4.8 drive that I would like to have as an
> independent drive e.g. /dev/hda or whatever it needs to be.
>
> What I DO NOT want to happen is for me to accidentally mess up my
> new Centos 5.5 system :-)!!
>
> Questions:
>
> * Is it possible to "remove" /dev/hdd from the LVM - at least it
> appears to be part of it
> * Once removed, format it as EXT3 and mount it as /dev/hda (or
> /dev/hdd)
>
> For this I am swimming in unknown waters.
>
> Todd
>
> Disk /dev/hdc: 251.0 GB, 251000193024 bytes
> 255 heads, 63 sectors/track, 30515 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
>      Device Boot      Start         End      Blocks   Id  System
> /dev/hdc1   *           1          13      104391   83  Linux
> /dev/hdc2              14       30515   245007315   8e  Linux LVM
>
> Disk /dev/hdd: 163.9 GB, 163928604672 bytes
> 255 heads, 63 sectors/track, 19929 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
>      Device Boot      Start         End      Blocks   Id  System
> /dev/hdd1   *           1          13      104391   83  Linux
> /dev/hdd2              14       19929   159975270   8e  Linux LVM
>
> Disk /dev/sda: 81.9 GB, 81964302336 bytes
> 255 heads, 63 sectors/track, 9964 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
>      Device Boot      Start         End      Blocks   Id  System
> /dev/sda1               1        9964    80035798+   7  HPFS/NTFS
>
>
For working with LVM's, I've found that the "system-config-lvm" GUI tool 
is excellent. It's really great for when I want to reduce a logical 
volume, since it handles resizing both the file system and the volume 
group for you).

It will display all of your drives/partitions and let you adjust them 
for what you describe.

Please take a look at it and feel free to post any questions.

Charlie

P.S. I'm a Unix Admin, so I love the command line ... this is one of the 
few times where I recommend a GUI tool over typing the commands.