Procedure

[root@nodo2 ~]# xe sr-list
uuid ( RO)                : 1d60cb3e-8884-6d82-2244-9b3288b2f577
          name-label ( RW): XenServer Tools
    name-description ( RW): XenServer Tools ISOs
                host ( RO): nodo2
                type ( RO): iso
        content-type ( RO): iso


uuid ( RO)                : 86385dbe-282a-1fac-d894-43532e4fef85
          name-label ( RW): Local storage
    name-description ( RW):
                host ( RO): nodo2
                type ( RO): ext
        content-type ( RO): user

[root@nodo2 ~]# xe pbd-list sr-uuid=86385dbe-282a-1fac-d894-43532e4fef85
uuid ( RO)                  : 4b9b4500-9805-0840-e0d1-7fbeccea1302
             host-uuid ( RO): f484d571-c048-47ca-92e5-298695abeb08
               sr-uuid ( RO): 86385dbe-282a-1fac-d894-43532e4fef85
         device-config (MRO): device: /dev/disk/by-id/ata-HITACHI_H7210CA30SUN1.0T_1046AGZNKL_JPW9K0HD3GZNKL-part3
    currently-attached ( RO): false

[root@nodo2 ~]# xe pbd-unplug uuid=4b9b4500-9805-0840-e0d1-7fbeccea1302

[root@nodo2 ~]# xe sr-forget uuid=86385dbe-282a-1fac-d894-43532e4fef85

[root@nodo2 ~]# sed -i 's/metadata_read_only = 1/metadata_read_only = 0/' /etc/lvm/lvm.conf

[root@nodo2 ~]# lvremove /dev/XSLocalEXT-86385dbe-282a-1fac-d894-43532e4fef85/86385dbe-282a-1fac-d894-43532e4fef85
Do you really want to remove active logical volume 86385dbe-282a-1fac-d894-43532e4fef85? [y/n]: y
  Logical volume "86385dbe-282a-1fac-d894-43532e4fef85" successfully removed

[root@nodo2 ~]# vgs
  VG                                              #PV #LV #SN Attr   VSize   VFree
  XSLocalEXT-86385dbe-282a-1fac-d894-43532e4fef85   1   0   0 wz--n- 890.00g 890.00g

[root@nodo2 ~]# vgre
vgreduce  vgremove  vgrename

[root@nodo2 ~]# vgremove XSLocalEXT-86385dbe-282a-1fac-d894-43532e4fef85
  Volume group "XSLocalEXT-86385dbe-282a-1fac-d894-43532e4fef85" successfully removed

[root@nodo2 ~]# pvs
  PV         VG   Fmt  Attr PSize   PFree
  /dev/sda3       lvm2 ---  890.01g 890.01g

[root@nodo2 ~]# pvremove /dev/sda3
  Labels on physical volume "/dev/sda3" successfully wiped

[root@nodo2 ~]# pvs
[root@nodo2 ~]# lvs
[root@nodo2 ~]# vgs

[root@nodo2 ~]# sgdisk -R /dev/sdb /dev/sda
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=1:fd00 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=2:fd00 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=3:fd00 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=4:ef02 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=5:fd00 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# sgdisk --typecode=6:fd00 /dev/sdb
The operation has completed successfully.

[root@nodo2 ~]# mdadm --create /dev/md0 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb1 missing
mdadm: /dev/sdb1 appears to contain an ext2fs file system
       size=18874304K  mtime=Thu Jun 16 15:08:17 2016
Continue creating array? y
mdadm: array /dev/md0 started.

[root@nodo2 ~]# mdadm --create /dev/md1 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb2 missing
mdadm: array /dev/md1 started.
[root@nodo2 ~]# mdadm --create /dev/md2 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb3 missing
mdadm: /dev/sdb3 appears to contain an ext2fs file system
       size=933245568K  mtime=Thu Jun  2 12:33:29 2016
Continue creating array? y
mdadm: array /dev/md2 started.

[root@nodo2 ~]# mdadm --create /dev/md3 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb4 missing
mdadm: array /dev/md3 started.

[root@nodo2 ~]# mdadm --create /dev/md4 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb5 missing
mdadm: array /dev/md4 started.

[root@nodo2 ~]# mdadm --create /dev/md5 --level=1 --raid-devices=2 --metadata=0.90 /dev/sdb6 missing
mdadm: array /dev/md5 started.

[root@nodo2 ~]# mkfs.ext3 /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1179648 inodes, 4718576 blocks
235928 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
144 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

[root@nodo2 ~]# mkfs.ext3 /dev/md4
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
262144 inodes, 1048560 blocks
52428 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1073741824
32 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

[root@nodo2 ~]# mount /dev/md0 /mnt
[root@nodo2 ~]# mkdir -p /mnt/var/log
[root@nodo2 ~]# mount /dev/md4 /mnt/var/log
[root@nodo2 ~]# cp -xR --preserve=all / /mnt

[root@nodo2 ~]# echo "MAILADDR root" > /mnt/etc/mdadm.conf
[root@nodo2 ~]# echo "auto +imsm +1.x -all" >> /mnt/etc/mdadm.conf
[root@nodo2 ~]# echo "DEVICE /dev/sd*[a-z][1-9]" >> /mnt/etc/mdadm.conf

[root@nodo2 ~]# mdadm --detail --scan >> /mnt/etc/mdadm.conf
[root@nodo2 ~]# cp /mnt/etc/mdadm.conf /etc
[root@nodo2 ~]# sed -i 's/LABEL=root-[a-zA-Z\-]*/\/dev\/md0/' /mnt/etc/fstab
[root@nodo2 ~]# sed -i 's/LABEL=swap-[a-zA-Z\-]*/\/dev\/md5/' /mnt/etc/fstab
[root@nodo2 ~]# sed -i 's/LABEL=logs-[a-zA-Z\-]*/\/dev\/md4/' /mnt/etc/fstab
[root@nodo2 ~]# e2label /dev/sda1 |xargs -t e2label /dev/sdb1
e2label /dev/sdb1 root-hapfuo

[root@nodo2 ~]# mount --bind /dev /mnt/dev
[root@nodo2 ~]# mount --bind /sys /mnt/sys
[root@nodo2 ~]# mount --bind /proc /mnt/proc
[root@nodo2 ~]# chroot /mnt  /bin/bash

[root@nodo2 /]# grub-install /dev/sdb
Installing for i386-pc platform.
grub-install: warning: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
grub-install: warning: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
Installation finished. No error reported.

[root@nodo2 /]# cp /boot/initrd-$(uname -r).img /boot/initrd-$(uname -r).img.bck

[root@nodo2 /]# dracut --mdadmconf --fstab --add="md mdraid" --filesystems "ext3 tmpfs devpts sysfs proc" --add-drivers="raid1 raid456 mdraid1x mdraid09" --force /boot/initrd-$(uname -r).img $(uname -r) -M
dracut module 'md' cannot be found or installed.

[root@nodo2 /]# sed -i 's/quiet/rd.auto rd.auto=1 rhgb quiet/' /boot/grub/grub.cfg
[root@nodo2 /]# sed -i 's/LABEL=root-[a-zA-Z\-]*/\/dev\/md0/' /boot/grub/grub.cfg
[root@nodo2 /]# exit

[root@nodo2 ~]# cp /mnt/boot/initrd-3.10.0+10.img /boot/
cp: overwrite ‘/boot/initrd-3.10.0+10.img’? y


[root@nodo2 ~]# sed -i 's/quiet/rd.auto rd.auto=1 rhgb quiet/' /boot/grub/grub.cfg
[root@nodo2 ~]# sed -i 's/LABEL=root-[a-zA-Z\-]*/\/dev\/md0/' /boot/grub/grub.cfg

[root@nodo2 ~]# reboot