In Linux, there are basically two methods a disk or drive can be partitioned. One way is by using the standard partitioning method, and the other is by using the LVM partitioning method.
A standard partition is a method in Linux a drive/disk is splitted/partitioned.
Disks topology in Linux is in the form of (sda, sdb, sdc, sdn..), from first disk to the last disk respectively, and can be partitioned in a standard method as (sda1, sda2, sdb1, sdb2, sdn1, sdn2, etc).
[root@HQDEV1 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 15G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 14G 0 part
├─rhel-root 253:0 0 12.5G 0 lvm /
└─rhel-swap 253:1 0 1.5G 0 lvm [SWAP]
sdb 8:16 0 5G 0 disk
└─sdb1 8:17 0 1G 0 part /test1
sr0 11:0 1 7.3G 0 rom /run/media/root/RHEL-8-1-0-BaseOS-x86_64
From the screen-shot above, you can see that the disk, “sda” is partitioned to sda1 and sda2, while the “sdb” disk is partitioned to sdb1 only. It is very possible to use only one partitioning method which can be standard or LVM, or both partitioning methods. You will understand better as we move on in this subject matter.
The utilities that can be used to create a standard partition in Linux are “fdisk” and “gdisk”. We will see how these utilities can be used with examples in the “ACTION TIME” section.
Going forward, there are some important storage concepts we need to understand before we proceed. They are filesystem, mount point, and “/etc/fstab” file.
A filesystem in this context is a way of arranging, or rather, a system of arranging files on a drive. Just as books can be arranged in a shelve horizontally or vertically, a filesystem is also a system files can be arranged on a device.
There are a lot of filesystems available in Linux. The most commonly used ones are; xfs, ext4, ext3, ext2, btrfs and gfs2. So, files can be arranged on a disk in any of these following systems.
The xfs filesystem is the default filesystem in RHEL 7 and above. Xfs has been considered to be a very good filesystem for a basic storage. It is flexible and has good tuning options.
The ext (2,3, and 4) were the default filesystems in RHEL6 and below. It uses a flat index file and not very scalable as compared to xfs, while btrfs is a copy-on-write filesystem. One advantage of using brtfs filesystem is to eradicate the need for journaling.
The gfs2 filesystem is used for active active clustering. For active passive type of clustering, any of the ext filesystems or the xfs filesystem can be used.
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When a disk is partitioned, a filesystem has to be created on the partition before it can be used. In other words, a disk has to be partitioned with one particular filesystem.
To know the filesystem of a particular partition, use the command, blkid |grep
OR
fsck -N <partition>
[root@HQDEV1 ~]# blkid |grep /dev/sdb1
/dev/sdb1: LABEL="tekneed_fs" UUID="fe48facc-c481-4429-93d2-77e4ac0afc89" TYPE="ext4" PARTLABEL="Linux filesystem" PARTUUID="245ddd05-cdcb-4128-ba75-28eb026dcbaf"
[root@HQDEV1 ~]#
OR
[root@HQDEV1 ~]# fsck -N /dev/sdb1
fsck from util-linux 2.32.1
[/usr/sbin/fsck.ext4 (1) -- /dev/sdb1] fsck.ext4 /dev/sdb1
mkfs.<file-system type> /dev/<block or partition>
[root@HQDEV1 ~]# mkfs.ext3 /dev/sdb1
In the “ACTION TIME”[link] section, we will see how all of these are done with examples.
mkfs.<fileystem-type> --help
example is #mkfs.ext4 --help
Another important concept is mount point.
A mount point is a special directory or a path where drives or partitions are mounted on.
If you followed the “Learn Linux from scratch” series course on this site, where we discussed filesystem hierarchy and structure, you would know that the default mount point in Linux is “/mnt”.
You can mount any device on this directory if you don’t wish to create a mount point.
To see all the drives and partitions mounted on a Linux system, use the command,
[root@HQDEV1 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 886M 0 886M 0% /dev
tmpfs tmpfs 904M 0 904M 0% /dev/shm
tmpfs tmpfs 904M 9.7M 894M 2% /run
tmpfs tmpfs 904M 0 904M 0% /sys/fs/cgroup
/dev/mapper/rhel-root xfs 13G 4.4G 8.2G 35% /
/dev/sda1 xfs 1014M 180M 835M 18% /boot
tmpfs tmpfs 181M 1.2M 180M 1% /run/user/42
tmpfs tmpfs 181M 4.6M 177M 3% /run/user/0
/dev/sr0 iso9660 7.4G 7.4G 0 100% /run/media/root/RHEL-8-1-0-BaseOS-x86_64
From the output of the command above, you can see the drives and partitions(filesystems), its type, sizes, used and available sizes and mount points.
To create a mount point, use the “mkdir” command.
[root@HQDEV1 ~]# mkdir /tekneed/victor
sometimes, you may want to use the “-p” option which means (no error if existing, make parent directories as needed)
[root@HQDEV1 ~]# mkdir -p /tekneed/victor
How To Manually Mount a disk or a partition In Linux
After a mount point has been created, the next thing is to mount the drive/partition or map a drive/partition to the mount point.
mount /dev/<drive-or-partition> <mount-point>
[root@HQDEV1 ~]# mount /dev/sdb1 /tekneed/victor
Sometimes, when a system reboots, a partition or a device number/topology may change. For example, “/dev/sdb1” may change to “/dev/sdc1”.
To avoid this and make the device numbers persistent after a reboot, always mount devices/partitions with their labels or UUIDs.
mount LABEL=<label-name> <mount-point>
We will see how all of these are done with examples in the “ACTION TIME” section.
As an administrator, if you wish to unmount a device or a partition, use the command,
umount /dev/<device-or-partition>
for example
[root@HQDEV1 ~]# umount /dev/sdc2
To list all the disks with their partitions on a Linux system, use the command, “lsblk” (list blocks)
fdisk/partitioning, manage/extend filesystems - xfs/ext4, LVM, check filesystem and disk usage - df/du, /etc/fstab
ii. Fdisk in linux
iii. How to modify EBS volumes ?
a. Requirements when modifying volumes
b. Request modifications to your EBS volumes
c. Monitor the progress of volume modifications
d. Extend a Linux file system after resizing a volume