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. Run the following command to mount the partition again:

     mount Disk partition Mount point

     In this example, run the following command:

     mount /dev/vdb1 /mnt/sdc

     Perform the following steps to enable automatic partition mounting at system start:

  2. Run the following command to query the partition UUID:

     blkid Disk partition

     In this example, run the following command to query the UUID of the /dev/vdb1 partition:

     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. Run the following command to 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

     The preceding content is used for reference only. Add the information that is used in the environment. The parameters are described as follows:

     • The first column indicates the partition UUID obtained in 2.
     • The second column indicates the directory on which the partition is mounted. You can query the mount point using the df -TH command.
     • The third column indicates the file system format of the partition. You can query the file system format using the df -TH command.
     • The fourth column indicates the partition mount option. Normally, this parameter is set to defaults.
     • The fifth column indicates the Linux dump backup option.
       • 0: Linux dump backup is not used. Normally, dump backup is not used, and you can set this parameter to 0.
       • 1: Linux dump backup is used.
     • The sixth column indicates the fsck option, that is, whether to use fsck to check the attached disk during startup.
       • 0: not use fsck.
       • If the mount point is the root partition (/), this parameter must be set to 1.

         When 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.

     Perform the following operations to verify the automatic mounting function:

     1. Run the following command to unmount the partition:

        umount Disk partition

        In this example, run the following command:

        umount /dev/vdb1

     2. Run the following command to reload all the content in the /etc/fstab file:

        mount -a

     3. Run the following command to 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, automatic mounting has been configured:

        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.