[linux-lvm] Setting up LVM with existing RAID 1 (Mirror)

[linux-lvm] Setting up LVM with existing RAID 1 (Mirror)

[Rehan]

Hi All,
I have SUSE 9.0 SP2 installed with two 70GB Hardware
RAID 1(Its a DEll Poweredge mirrored). We have an /opt
partition which is alomst full. We need to use LVM to
expand OPT. We have plenty of free space on the disk.
I think LVM2 is installed but not configured since we
have a lvm.conf file under /etc/lvm. I have not used
LVM before so I was wondring if you guys can help me
out with what needs to be done to expand /opt. My
first question is it possible to expand opt using LVM
with existing RAID 1. My second question is do we have
to break the mirror and what are the steps involved to
get it done? If you guys know of any document that I
can read and figure this out it would be great. 

dda006:/etc/lvm # lvscan
  No volume groups found

dda006:/etc/lvm # fdisk -l

Disk /dev/sda: 73.2 GB, 73274490880 bytes
255 heads, 63 sectors/track, 8908 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id
 System
/dev/sda1   *           1         784     6297448+  83
 Linux
/dev/sda2             785        8907    65247997+   f
 W95 Ext'd (LBA)
/dev/sda5             785        1176     3148708+  82
 Linux swap
/dev/sda6            1177        1960     6297448+  83
 Linux
/dev/sda7            1961        2744     6297448+  83
 Linux
/dev/sda8            2745        3528     6297448+  83
 Linux
/dev/sda9            3529        3790     2104483+  83
 Linux
/dev/sda10           3791        4052     2104483+  83
 Linux
dda006:/etc/lvm # df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             6.1G  1.2G  4.9G  20% /
tmpfs                1013M   12K 1013M   1% /dev/shm
/dev/sda9             2.1G  1.4G  699M  66% /home
/dev/sda8             6.1G  5.6G  435M  93% /opt
/dev/sda10            2.1G  1.3G  778M  63% /tmp
/dev/sda6             6.1G  2.5G  3.6G  41% /usr
/dev/sda7             6.1G  149M  5.9G   3% /var
hco431brgdda006:/etc/lvm #


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 

Re: [linux-lvm] Setting up LVM with existing RAID 1 (Mirror)

[Dieter Stüken]

Hi Rehan,

If I have a look at your partition table

> Disk /dev/sda: 73.2 GB, 73274490880 bytes
> 255 heads, 63 sectors/track, 8908 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>    Device Boot Start    End      Blocks   Id System
> /dev/sda1   *      1    784     6297448+  83 Linux
> /dev/sda2        785   8907    65247997+   f W95 Ext'd (LBA)
> /dev/sda5        785   1176     3148708+  82 Linux swap
> /dev/sda6       1177   1960     6297448+  83 Linux
> /dev/sda7       1961   2744     6297448+  83 Linux
> /dev/sda8       2745   3528     6297448+  83 Linux
> /dev/sda9       3529   3790     2104483+  83 Linux
> /dev/sda10      3791   4052     2104483+  83 Linux

it seems /dev/sda2 is a container holding sda5-10 as logical 
partitions. This concept is similar to a LVM layout, where sda2
would be a physical volume (PV) containing several logical volumes
(LV) like /opt /home swap etc. 

But even if you have a lot of free space within sda2, it does
not help you, as long as the whole disk is occupied by sda2.
You have to get rid of all the logical partitions :-(

But you may keep your root partition :-)

step 1: erase sda5-10

You may copy /usr /var and /home into your root partition
(use: cp -a). Swap can be disabled for a while. But you
have to save /opt (may be /tmp) to an additional disk.
Then you are able delete sda5-10.

step 2: initialize LVM / create a logical volume

Turn sda2 into a PV with "pvcreate /dev/sda2".
Create a logical volume: "vgcreate volume1 /dev/sda2".
You may choose any other name instead of "volume1".
Now you create your LVs as needed:

lvcreate volume1 -n swap -l 2G
lvcreate volume1 -n usr -l 6G
lvcreate volume1 -n opt -l 12G
....

mkswap /dev/volume1/swap
mke2fs /dev/volume1/usr
mke2fs /dev/volume1/opt
...

step 3: copy back the data to your newly created LVs.

conclusion:

Your new LVs have real names instead of just /dev/sda8.
Any free space you have may be assigned to any of your
LVs, as they don't have to be continuous any more.
Anyway, dealing with additional disk space is MUCH
easier once after you started using LVM. 

Dieter.