Centos 7.2 Convert single LVM to RAID Mirror Reinstall BootLoader Post: 302971389

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Operating Systems Linux Centos 7.2 Convert single LVM to RAID Mirror Reinstall BootLoader Post 302971389 by Clovis_Sangrail on Tuesday 19th of April 2016 03:58:39 PM

04-19-2016

Registered User

Centos 7.2 Convert single LVM to RAID Mirror Reinstall BootLoader

Hello,
I am trying to convert a single-drive Centos 7.2 installation with LVM into a two-disk mdadm mirror with mrrored LVM. I was able to follow the excellent instructions at:

HTML Code:

http://www.dgoradia.com/creating-a-raid1-mirrored-on-an-existing-centos-on-lvm/

and did create a two-disk mirror of both the original boot partition and the LVM partition. When I boot off a live Centos 7.2 DVD with the mirrored drives installed it does find the mirrors, and I can fsck and mount the boot and LVM filesystems in it.

Code:

[root@new-host-4 ~]# lsblk
NAME              MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda                 8:0    0 465.8G  0 disk  
├─sda1              8:1    0     1G  0 part  
│ └─md126           9:126  0  1024M  0 raid1 
└─sda2              8:2    0   115G  0 part  
  └─md127           9:127  0   115G  0 raid1 
    ├─centos-root 253:3    0    40G  0 lvm   
    ├─centos-swap 253:4    0     9G  0 lvm   
    ├─centos-home 253:5    0    25G  0 lvm   
    └─centos-var  253:6    0    40G  0 lvm   
sdb                 8:16   0 465.8G  0 disk  
├─sdb1              8:17   0     1G  0 part  
│ └─md126           9:126  0  1024M  0 raid1 
└─sdb2              8:18   0   115G  0 part  
  └─md127           9:127  0   115G  0 raid1 
    ├─centos-root 253:3    0    40G  0 lvm   
    ├─centos-swap 253:4    0     9G  0 lvm   
    ├─centos-home 253:5    0    25G  0 lvm   
    └─centos-var  253:6    0    40G  0 lvm   
sr0                11:0    1   4.4G  0 rom   /run/initramfs/live
loop0               7:0    0    20K  1 loop  
loop1               7:1    0   4.3M  1 loop  
└─live-osimg-min  253:2    0     8G  1 dm    
loop2               7:2    0     1G  1 loop  
loop3               7:3    0     8G  1 loop  
├─live-rw         253:0    0     8G  0 dm    /
├─live-base       253:1    0     8G  1 dm    
└─live-osimg-min  253:2    0     8G  1 dm    
loop4               7:4    0   512M  0 loop  
└─live-rw         253:0    0     8G  0 dm    /
[root@new-host-4 ~]#

However these instructions are specific to Centos 6, and the section for installing a bootloader on the new mirror completely does not apply in Centos 7. In Centos 7.2 there does not seem to be any commandline utility that provides a "grub>" command prompt, ant the grub binary itself is replaced by a bunch of "grub2-*" executables.

Can anyone explain how to reinstall the bootloader on the new mirror? The Centos 6 instructions say it must be installed separately on sda1 and sdb1.

Last edited by Clovis_Sangrail; 04-19-2016 at 07:34 PM..

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LEARN ABOUT SUSE

pvresize

PVRESIZE(8)						      System Manager's Manual						       PVRESIZE(8)

NAME

       pvresize - resize a disk or partition in use by LVM2

SYNOPSIS

       pvresize [-d|--debug] [-h|--help] [-t|--test] [-v|--verbose] [--setphysicalvolumesizesize] PhysicalVolume [PhysicalVolume...]

DESCRIPTION

       pvresize resizes PhysicalVolume which may already be in a volume group and have active logical volumes allocated on it.

OPTIONS

       See lvm(8) for common options.

       --setphysicalvolumesize size
	      Overrides the automatically-detected size of the PV.  Use with care, or prior to reducing the physical size of the device.

EXAMPLES

       Expand the PV on /dev/sda1 after enlarging the partition with fdisk:

       pvresize /dev/sda1

       Shrink the PV on /dev/sda1 prior to shrinking the partition with fdisk (ensure that the PV size is appropriate for your intended new parti-
       tion size):

       pvresize --setphysicalvolumesize 40G /dev/sda1

RESTRICTIONS

       pvresize will refuse to shrink PhysicalVolume if it has allocated extents after where its new end would be. In the future, it should  relo-
       cate these elsewhere in the volume group if there is sufficient free space, like pvmove does.

       pvresize won't currently work correctly on LVM1 volumes or PVs with extra metadata areas.

SEE ALSO

       lvm(8), pvmove(8), lvresize(8), fdisk(8)

Sistina Software UK					 LVM TOOLS 2.02.67(2) (2010-06-04)					       PVRESIZE(8)

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