Repartition server after Proxmox image installation from rescue mode

repartition-proxmox-rescue-mode.txt

We want to split a 8TB disks into:
-1TB RAID1 for root "/"
-1TB RAID1 for extra things "backups, templates, etc."
-6TB LVM-Thin (with LVM mirroring) for Containers and VM


Boot into rescue mode

#Active probes:
modprobe md
modprobe linear
modprobe multipath
modprobe raid0
modprobe raid1
modprobe dm-mod 

#### Mount disks and copy array info and scan it (the root partition "/" in this case is in md127)
/usr/local/sbin/mountall.sh
fdisk -l
mdadm --examine --scan

# Copy the "normal boot" mdadm info into "rescue mode" etc, scan it  and check
cp /mnt/md127/etc/mdadm/mdadm.conf /etc/mdadm/mdadm.conf
mdadm -A --scan
fdisk -l
e2fsck -f /dev/md127

#### Unmount the partition, and start the process of shrinking the filesystem and the array
umount /mnt/md127
sudo mdadm -D /dev/md127 | grep -e "Array Size" -e "Dev Size" #just to check the array size
resize2fs /dev/md127 1000G #resize filesystem to 1000GB
mdadm --grow /dev/md127 --size=1073741824  #resize array size to 1024GB to keep some "space" and avoid problems
resize2fs /dev/md127 #resize again the filesystem to its maximum (1024GB)
mdadm --detail /dev/md127 #just check the array

# Remove one disk from array and resize partition/segment to something over 1024GB (1110000MB) and re-add and rescan
cat /proc/mdstat
mdadm /dev/md127 --fail /dev/sda4 --remove /dev/sda4
parted -a opt /dev/sda
  >> resizepart -> 4 -> 1110000
mdadm -a /dev/md127 /dev/sda4

cat /proc/mdstat
echo 1 > /sys/block/sda/device/rescan

# Do the same with the other disk

#### Until here we would already have the array shrinked to 1T with free space for the rest of the disk.

#### Ne we create 1 extra partition for whatever (backups, etc), for example in RAID1 (we could also use ZFS or whatever)
#Format a 1Tb partition in both disks in RAID1 (type 29)
fdisk /dev/sda
   >>n -> 5 -> +1T -> t -> 29
# Do the same with the other disk

# And create the array with the 2 disks
mdadm --create /dev/md128 --level=1 --raid-devices=2 /dev/sda5 /dev/sdb5
cat /proc/mdstat
# Create the file system with mk, mount it, and add it to fstab
mkfs.ext4 -L label-name /dev/md128
nano /etc/fstab
/dev/md128    /backups    ext4    defaults    0    1

#### Now we create the 6TB (or actually 5TB) LVM-Thin partition (using now type 31 that is LVM)
fdisk /dev/sda
    >>n -> 6 -> +6T -> t -> 31
# do the same (if we want it in mirror) with the other disk

# We create the physical volumes for each disk and the volume group of both
pvcreate /dev/sda6 /dev/sdb6
vgcreate -s128M lvm /dev/sda6 /dev/sdb6
vgdisplay lvm
vgs

# we now create the logical volume in "mirror1" mode (m1) at 97% to leave space for the poolmetadata so then -when we convert it to thin-pool- there won't any problems,
# If we don't want it to be thin-pool it could be done it at 100%

lvcreate -n data -m1 -l 97%VG lvm
lvconvert --type thin-pool --poolmetadatasize 1024M --chunksize 128 lvm/data
lvs -a -o name,copy_percent,devices lvm
mkfs.ext4 /dev/lvm/data

# now doing a fdisk it should show it like this

fdisk -l

Device          Start         End     Sectors  Size Type
/dev/sdb1        2048        4095        2048    1M BIOS boot
/dev/sdb2        4096     1052671     1048576  512M Linux swap
/dev/sdb3     1052672     2281471     1228800  600M Linux RAID
/dev/sdb4     2281472  2167968750  2165687279    1T Linux RAID
/dev/sdb5  2167969792  4315453439  2147483648    1T Linux RAID
/dev/sdb6  4315453440 15052871679 10737418240    5T Linux LVM

# to check partitions and mounts (we don't need to mount sdb6 partition for proxmox interface to use it, i think)
blkid
cat /etc/mtab