Why Can't I View the Attached Data Disk on the Server?

[root@ecs-test-0001 ~]# df -TH
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/vda1      ext4       43G  1.9G   39G   5% /
devtmpfs       devtmpfs  2.0G     0  2.0G   0% /dev
tmpfs          tmpfs     2.0G     0  2.0G   0% /dev/shm
tmpfs          tmpfs     2.0G  9.1M  2.0G   1% /run
tmpfs          tmpfs     2.0G     0  2.0G   0% /sys/fs/cgroup
tmpfs          tmpfs     398M     0  398M   0% /run/user/0
/dev/vdb1      ext4      106G   63M  101G   1% /mnt/sdc

Unlike the normal command output, only system disk /dev/vda1 is visible, but data disk /dev/vdb1 is missing from the command output.

Cause Analysis:

• Cause 1: New data disks are not formatted and partitioned by default, and an unformatted disk will not be listed in the command output. You must manually initialize the disk.

  For details, see Introduction to Data Disk Initialization Scenarios and Partition Styles.

• Cause 2: If a data disk cannot be found after the server is restarted, automatic partition mounting at system start may not be configured. Perform the following steps:
  1. Mount the data disk.

     mount Disk partition Mount point

     In this example, run the following command:

     mount /dev/vdb1 /mnt/sdc

     Perform the following steps to configure auto mount at system start:

  2. Query the partition UUID.

     blkid Disk partition

     In this example, the UUID of the /dev/vdb1 partition is queried.

     blkid /dev/vdb1

     Information similar to the following is displayed:

     [root@ecs-test-0001 ~]# blkid /dev/vdb1
     /dev/vdb1: UUID="0b3040e2-1367-4abb-841d-ddb0b92693df" TYPE="ext4"

     The UUID of the /dev/vdb1 partition is displayed.

  3. Open the fstab file using the vi editor.

     vi /etc/fstab

     Press i to enter editing mode.

  4. Move the cursor to the end of the file and press Enter. Then, add the following information:

     UUID=0b3040e2-1367-4abb-841d-ddb0b92693df /mnt/sdc                ext4    defaults        0 2

     In this example, the line starting with "UUID" is the information added. Edit this line to match the following format:

     • UUID: The UUID obtained in 2.
     • Mount point: The directory on which the partition is mounted. You can query the mount point using df -TH.
     • Filesystem: The file system format of the partition. You can query the file system format using df -TH.
     • Mount option: The partition mount option. Usually, this parameter is set to defaults.
     • Dump: The Linux dump backup option.
       • 0: Linux dump backup is not used. Usually, dump backup is not used, and you can set this parameter to 0.
       • 1: Linux dump backup is used.
     • fsck: The fsck option, which means whether to use fsck to check the disk during startup.
       • 0: The fsck option is not used.
       • If the mount point is the root partition (/), this parameter must be set to 1.

         If this parameter is set to 1 for the root partition, this parameter for other partitions must start with 2 because the system checks the partitions in the ascending order of the values.

  5. Press Esc, enter :wq, and press Enter.

     The system saves the configurations and exits the vi editor.

     Verify that the disk is auto-mounted at startup.

     1. Unmount the partition.

        umount Disk partition

        In this example, run the following command:

        umount /dev/vdb1

     2. Reload all the content in the /etc/fstab file.

        mount -a

     3. Query the file system mounting information.

        mount | grep Mount point

        In this example, run the following command:

        mount | grep /mnt/sdc

        If information similar to the following is displayed, auto mount has taken effect:

        root@ecs-test-0001 ~]# mount | grep /mnt/sdc
        /dev/vdb1 on /mnt/sdc type ext4 (rw,relatime,data=ordered)

Windows Data Disk

Symptom: A data disk has been attached to a Windows server on the management console, but the disk cannot be viewed on the server. For example, Volume (D:) was not shown in This PC of a Windows server running Windows Server 2012. Normally, Volume (D:) appears, as shown in Figure 1.

Figure 1 Volume (D:) appears

Solution: New data disks are not formatted and partitioned by default. Only formatted and partitioned drives show up in This PC. You must manually initialize the disk before it can be viewed here.

For details, see Introduction to Data Disk Initialization Scenarios and Partition Styles.