Disk & Filesystems - alex-aleyan/linux_wiki GitHub Wiki

Quick Cheat Sheet:

parted -l
parted -> mklabel
parted -> mkpart
fdisk -l
fdisk /dev/sdb
sfdisk -d /dev/sda
sfdisk -d /dev/sda | sfdisk --force /dev/sdb
mkfs.ext4 /dev/sdb1
mkfs.xfs /dev/mapper/vg_opt-lv_opt 

Locate the drive using ls -la /dev | grep sd. (look for devices named as sda or sdb or sdc which are partitioned as sda1, sda2...)

See if the drive is mounted by typing: mount

See where it's mounted by typing: df -TH /dev/sda or mount if /dev contains sdc1 and sdc2 for example, it means the partitions of the drive are mounted. Unmount them using umount or umount -l.

optionally see the size of the filesystem

• df -TH
• du -sh /a_dir or du -ah /a_dir or du -s ./* | sort -n

Partition the drive by launching the parted program:

• Type parted to launch the program (typing End: -0 will partition it to the end of drive).
• Type print to list all drives and their partitions (you can also use fdisk -l to get a more detailed list).
• Type mklabel gpt (> 2GB) or mklable msdos to make a label.
• Type mkpart to make a partition. Use enter/return key to skip all the settings except the Partition Type, Start and End (-0 will partition it to the end of drive):
  • mkpart primary ext4 0% 100%
  • set 1 lvm <on|off>
  • parted -s -a optimal mkpart primary 0% 100%

Create a File System by typing:

• mkfs.ext4 /dev/sdc1
• mkfs -t ext4 /dev/sdc1

Mount it by first creating a desired mount directory and then by typing mount /dev/sdc1 /media/stick_1

Add a label to file system:

e2label /dev/sda1 "my_lable"
blkid /dev/sda1
    LABEL="my_label"

• LVM Physical Volume - a partition (sda2 and sda3) created on a physical drive to be used to compose a Volume Group.
  • pvdisplay /dev/sda3 displays which Physical Volumes (partitions) were used to compose a Volume Group.
  • pvscan
• Volume Group - a collection of Physical Volume partitions used as a single virtual disk for Logic Volumes.
  • vgdisplay vg1 displays Volume Group's information.
• Logical Volume - a filesystem residing on a Volume Group.
  • lvdisplay vg1 For the Volume Group vg1, displays info on each Logic Volumes (file systems).

Growing LVM Logical Volumes:

• Short and Fast:

  • Check the current size of a Volume Group:
    • vgdisplay vg_1
    • lvdisplay
    • df -TH /mnt/my_lv/
  • Turn the added partition into a phys vol: pvcreate /dev/sdb
  • Expand the Volume Group size: vgextend vg_1 /dev/sdb
  • Expand the logical volume:
    • lvextend -L +100<b|B|s|S|k|K|m|M|g|G|t|T|p|P|e|E> /dev/mapper/vg_1-my_lv
    • lvextend -l +100%<FREE|ORIGIN|VG> /dev/mapper/vg_1-my_lv
    • lvextend 0l +100%FREE /dev/mapper/vg1-my_lv
  • Resize the filesystem on the Logic Volume to fit the new logical volume size:
    • CenOS6: resize2fs -p /dev/mapper/vg_1-my_lv
    • CentOS7: xfs_growfs /dev/mapper/vg_1-my_lv

• Long and Detailed:

  • Use these commands to see what goes on in terms of partitions and file systems:

    [root@test1 ~]# df –TH
    [root@test1 ~]# lvs; pvscan; pvdisplay; vgdisplay
    [root@test1 ~]# fdisk –l
    [root@test1 ~]# parted /dev/sda print
    [root@test1 ~]# mount
    

  • Add new partition to sda drive:

    [root@test1 ~]# fdisk
    Command (m for help): m
    Command (m for help): p
    Command (m for help): n
      Command action
        e extended
        p primary partition (1-4)
      p
    Partition Number (1-4): 3
    First Cylinder(1-2310, default 1): 
      Using default value 1
    Last Cylinder (1-2610), default 2610): 
      Using default value 2610
    Command (m for help): t
    Hex code (type L to list the codes): 8e #which corresponds to Linux LVM
    Command (m for help): w
    

  • Type this command to avoid problems with booting the machine after creating the partition above (Use CloneZilla image to remove the added partition parted rm /dev/sda YOUR_PARTITION_NUM ):

    partx -a /dev/sda
    

  • Check the partitions again:

    [root@test1 ~]# parted /dev/sda print
    

  • Make the ext4 file system on the partition we just created:

    [root@test1 ~]# mkfs.ext4 /dev/sda3
    

  • Initialize the /dev/sda3 partition as LVM physical volume so it can later be used as a part of LVM logical volumes:

    [root@test1 ~]# pvcreate /dev/sda3
    

  • Use pvscan to view physical volumes created by pvcreate; use pvdisplay to view more detailed information.

  • Determine the group name (here it's the group's name vg1):

    [root@test1 ~]# vgs
    VG 	#PV 	#LV 	#SN 	Attr 	VSize	VFree
    vg1	2	7	0	wz--n-	1.86t	0
    

  • Add the physical volume to LVM:

    [root@test1 ~]# vgextend vg1 /dev/sda3
    

  • Determine the name of your LVM:

    [root@test1 ~]# df -TH
    

  • Add space to LVM:

    [root@test1 ~]# lvextend –l +100%FREE /dev/mapper/vg1-root
    

  • Resize your filesystem:

    [root@test1 ~]# resize2fs /dev/mapper/vg1-root  (or xfs_growfs /dev/mapper/vg_1-my_lv on Centos7)
    

  • Display your logic volumes’ information:

    [root@test1 ~]# lvs
    

  • Display your volume groups’ information:

    [root@test1 ~]# vgs
    

Shrinking LVM Logical Volumes:

• Note:

  • we are shrinkg /dev/vg1/root Logical Volume.
  • we need to make sure that the filesystem is first reduced to a size A and then Logic Volume is reduced to a size B where A < B.
  • once Logic Volume is reduced to size B we can extend filesystem's size from size A to occupy as much of Logic Volume as possible.

• Using CloneZilla Disk, launch Command Line: CloneZilla -> Don't touch keymap -> Enter_Shell -> Command Line

• In Clonezilla, switch to the SuperUser mode: sudo su -

• Activate all logic volumes to make them avaiable to the shell: vgchange -a y

• Force the filesystem check on the Logic Volume of the interest: e2fsck -f /dev/vg1/root

• Resize the filesystem to 1.6T first before resizing the Logic Volume:

  resize2fs /dev/vg1/root 1600G #set to 1600G
  resize2fs /dev/vg1/root -200G  #reduce by 200G
  

• Reduce the size of the Logical Volume from 1.8T to 1.65T: lvreduce -L 1650G /dev/vg1/root

• Grow filesystem so that it occupies all of the Logical Volume: resize2fs /dev/vg1/root (or xfs_growfs /dev/mapper/vg_1-my_lv on Centos7)