Format a data disk for a Linux instance

After you attach a new data disk to an ECS instance, you must create at least one file system on the data disk and mount the file system. In this example, a new 20 GiB data disk attached to a CentOS 7.6 I/O optimized instance is used. The device name of the data disk is /dev/vdb. A single Master Boot Record (MBR) partition is created on the data disk and the ext4 file system is mounted to the partition.

1. Connect to the ECS instance. For more information, see Connect to an ECS instance.
2. Run the fdisk -l command to view all data disks attached to the ECS instance.
   Note If /dev/vdb is not displayed in the command output, the ECS instance does not have a data disk. Check whether the data disk is attached to the instance.
3. Run the following commands to create a single partition for the data disk:
   1. Run the fdisk -u /dev/vdb command to partition the data disk.
   2. Enter p to view the partition information of the data disk.
      In this example, the data disk is not partitioned.
   3. Enter n to create a new partition.
   4. Enter p to set the partition as the primary partition.
      Note When you create a single partition for a data disk, it must be a primary partition. If you want to create four or more partitions, enter e (extended) to create at least one extended partition.
   5. Type the partition number and press the Enter key.
      In this example, enter 1 to create one partition.
   6. Enter the number of the first available sector, or press the Enter key to use the default value 2048.
   7. Enter the number of the last sector.
      In this example, press the Enter key to use the default value.
   8. Enter p to view the intended partitions of the data disk.
   9. Enter w to start partitioning, and exit after partitioning is complete.

   [root@ecshost~ ]# fdisk -u /dev/vdb
   Welcome to fdisk (util-linux 2.23.2).
   Changes will remain in memory only, until you decide to write them.
   Be careful before using the write command.
   Device does not contain a recognized partition table
   Building a new DOS disklabel with disk identifier 0x3e60020e.
   
   Command (m for help): p
   Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
   Units = sectors of 1 * 512 = 512 bytes
   Sector size (logical/physical): 512 bytes / 512 bytes
   I/O size (minimum/optimal): 512 bytes / 512 bytes
   Disk label type: dos
   Disk identifier: 0x3e60020e
   Device Boot Start End Blocks Id System
   
   Command (m for help): n
   Partition type:
   p primary (0 primary, 0 extended, 4 free)
   e extended
   Select (default p): p
   Partition number (1-4, default 1): 1
   First sector (2048-41943039, default 2048):
   Using default value 2048
   Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039):
   Using default value 41943039
   Partition 1 of type Linux and of size 20 GiB is set
   
   Command (m for help): p
   
   Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
   Units = sectors of 1 * 512 = 512 bytes
   Sector size (logical/physical): 512 bytes / 512 bytes
   I/O size (minimum/optimal): 512 bytes / 512 bytes
   Disk label type: dos
   Disk identifier: 0x3e60020e
   Device Boot Start End Blocks Id System
   /dev/vdb1 2048 41943039 20970496 83 Linux
   
   Command (m for help): w
   The partition table has been altered!
   
   Calling ioctl() to re-read partition table.
   Syncing disks.

4. Run the fdisk -lu /dev/vdb command to view the new partition.
   If information about /dev/vdb1 appears, the new partition is created.

   [root@ecshost~ ]# fdisk -lu /dev/vdb
   
   Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
   Units = sectors of 1 * 512 = 512 bytes
   Sector size (logical/physical): 512 bytes / 512 bytes
   I/O size (minimum/optimal): 512 bytes / 512 bytes
   Disk label type: dos
   Disk identifier: 0x3e60020e
   
   Device Boot Start End Blocks Id System
   /dev/vdb1 2048 41943039 20970496 83 Linux

5. Run the mkfs.ext4 /dev/vdb1 command to create a file system in the new partition.

   In this example, an ext4 file system is created. You can modify the mkfs.ext4 command to create other file systems. For example, if you want to share files between the Linux, Windows, and Mac systems, you can run the mkfs.vfat /dev/vdb1 command to create a Virtual File Allocation Table (VFAT) file system.

   [root@ecshost~ ]# mkfs.ext4 /dev/vdb1
   
   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
   1310720 inodes, 5242624 blocks
   262131 blocks (5.00%) reserved for the super user
   First data block=0
   Maximum filesystem blocks=2153775104
   160 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

6. Write the information of the new partition to /etc/fstab to enable automatic partition mounting when the instance is started.
   1. Run the cp /etc/fstab /etc/fstab.bak command to back up etc/fstab.
   2. Run the echo `blkid /dev/vdb1 | awk '{print $2}' | sed 's/\"//g'` /mnt ext4 defaults 0 0 >> /etc/fstab command to write the information of the new partition to the /etc/fstab file.

      You can separately mount the data disk as a folder to store web pages. In this case, the /mnt portion in the command must be replaced with the intended mount point folder path.

      Note

      • We recommend that you use a Universally Unique Identifier (UUID) in /etc/fstab to reference the new partition. You can run the blkid command to obtain the UUID of the new partition.
      • The Ubuntu 12.04 operating system does not support barriers. You must run the echo '`blkid /dev/vdb1 | awk '{print $3}' | sed 's/\"//g'` /mnt ext4 barrier=0 0 0' >> /etc/fstab command to write the information of the new partition into the /etc/fstab file.
7. Run the cat /etc/fstab command to view the information of the new partition in /etc/fstab.

   [root@ecshost~ ]# cat /etc/fstab
   #
   # /etc/fstab
   # Created by anaconda on Wed Dec 12 07:53:08 2018
   #
   # Accessible filesystems, by reference, are maintained under '/dev/disk'
   # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
   #
   UUID=d67c3b17-255b-4687-be04-f29190d4**** / ext4 defaults 1 1
   UUID=a4c73111-3a33-4569-a90c-b6d2e953**** /mnt ext4 defaults 0 0

8. Run the mount /dev/vdb1 /mnt command to mount the file system.
   If the information of the new file system appears after you run the df -h command, the file system is mounted.

   [root@ecshost~ ]# mount /dev/vdb1 /mnt
   [root@ecshost~ ]# df -h
   
   Filesystem Size Used Avail Use% Mounted on
   /dev/vda1 40G 1.6G 36G 5% /
   devtmpfs 234M 0 234M 0% /dev
   tmpfs 244M 0 244M 0% /dev/shm
   tmpfs 244M 484K 244M 1% /run
   tmpfs 244M 0 244M 0% /sys/fs/cgroup
   tmpfs 49M 0 49M 0% /run/user/0
   /dev/vdb1 20G 45M 19G 1% /mnt