Initializing cloud disks (larger than 2TB)

Last updated: 2019-10-30 10:29:15

PDF

Scenario

This article provides a guide to cloud disk initialization operations by taking cloud disk with a capacity greater than or equal to 2TB as an example. For more information, see Initialization Scenarios.
MBR supports disk with a maximum capacity of 2TB. When you partition disk with a capacity greater than 2TB, we recommend you use GPT as the partition format. For Linux operating systems, when GPT is chosen as the partition format, fdisk partition tools can no longer be used, instead parted tools must be used.

Notes

  • Formatting a data disk will erase all data. Please ensure that the data disk does not contain data, or that important data has been backed up.
  • To avoid service exceptions, ensure before formatting that the CVM has stopped external services.

Prerequisites

You have mounted the cloud disk to a CVM.

Directions

Initializing cloud disks (Windows)

This article uses the Windows Server 2012 operating system as an example. The formatting operations on different operating systems may vary. This article is for reference only.

  1. Log in to the Windows Cloud Virtual Machine.
  2. In the CVM desktop, click to enter the Server Manager page.
  3. In the left navigation tree, click File and Storage Services.
  4. In the left navigation tree, select Volume>Disk.

If the newly added disk is in offline status (as shown in the figure above), you must execute Step 5 before executing Step 6 to perform initialization. In other cases, you can directly execute Step 6 to perform initialization.


5. Disk list is shown in the right-side pane. Right click the row where 1 is located, and select Online in the menu to put it online. The status of 1 changes from Offline to Online.

6. Right click the row where 1 is located, and select Initialize in the menu.
7. Follow instructions on the interface, and click Yes.
8. After initialization, the partition of 1 changes from Unknown to GPT. Right click the row where 1 is located and select New Simple Volume in the menu.
9. In the pop-up New Volume Wizard dialog box, follow instructions on the interface and click Next.
10. Select the server and disk, and click Next.
11. Specify the volume size according to actual circumstances. The default is the largest value. Click Next.
12. Assign a drive letter, and click Next.
13. Select Format this volume with the following settings, set parameters according to actual circumstances, format the partition, and click Next to complete partition creation.
14. After confirming the information contains no errors, click Create.
15. Wait for the system to complete the creation of the new volume, and then click Close.
After completing initialization, enter the My Computer interface to view the new disk.

Initializing cloud disks (Linux)

Select the initialization method according to your actual use scenario:

  • If the entire disk is presented as one independent partition (that is, there are not multiple logical disks such as vdb1 and vdb2), we strongly recommend you not use partitions, and directly create the file system on bare devices.
  • If the entire disk needs to be presented as multiple logical partitions (that is, there are multiple logical disks), you need to perform the partitioning first, then create the file system on a partition.

Creating file systems on bare devices

  1. Log in to the Linux Cloud Virtual Machine.
  2. Execute the following command as the root user to view the disk name.
    fdisk -l
    Returned information is similar to what is shown in the following figure, which indicates that the current CVM has two disks, “/dev/vda” is the system disk, and “/dev/vdb” is the newly created data disk.
  3. Execute the following command to create a file system on the “/dev/vdb” bare device.
    mkfs -t <File system format> /dev/vdb
    The partition size supported by different file systems varies. Select an appropriate file system according to your actual needs. In the following example, EXT4 is set as the file system:
    mkfs -t ext4 /dev/vdb

    The formatting takes a while, please pay attention to the system’s running status, and do not exit.

  4. Execute the following command to create a new mounting point.
    mkdir <Mounting point>
    Take the newly created mounting point /data as an example:
    mkdir /data
  5. Execute the following command to mount the newly created partition to the newly created mounting point.
    mount /dev/vdb <Mounting point>
    Take the newly created mounting point /data as an example:
    mount /dev/vdb /data
  6. Execute the following command to view the mounting results.
    df -TH

    If you do not need to set automatic disk mounting at startup, skip the following steps.

  7. Confirm the mounting method and obtain the corresponding information.
    You can choose to use an elastic cloud disk’s soft link, file system’s UUID (universally unique identifier) or device name to automatically mount a disk, according to your business needs. The related description and information acquisition methods are as follows:
    Mounting method Pros and cons Information acquisition method
    Use the soft link of the elastic cloud disk(Recommended) Pros:The soft link of each elastic cloud disk is fixed and unique, and will not change along with operations such as mounting, unmounting, and formatting partitions.
    Cons:Only elastic cloud disks can use soft links. They cannot sense the formatting operation of the partition.
    Execute the following command to view the soft link of the elastic cloud disk.
    ls -l /dev/disk/by-id
    Use a file system’s UUID Automatic mounting configuration may become invalid due to changes in a file system’s UUID.
    For example, reformatting a file system will change the UUID of the file system.
    Execute the following command to view the UUID of the file system.
    blkid /dev/vdb
    Use device name Automatic mounting configuration may become invalid due to changes in device name.
    For example, during data migration, the elastic cloud disk on the CVM is unmounted and then remounted. When the operating system recognizes the file system again, the device name may change.
    Execute the following command to view the device name.
    fdisk -l
  8. Backup the /etc/fstab file.
  9. Execute the following command to use VI editor to open the /etc/fstab file.
    vi /etc/fstab
  10. Press i to enter editing mode.
  11. Move the cursor to the end of the file and press Enter, then add the following content.
    <Device information> <Mounting point> <File system format> <File system installation option> <File system dump frequency> <File system check sequence at launch>
    • (Recommended) Take automatic mounting using the soft link of an elastic cloud disk as an example. Add the following to the previous example:
      /dev/disk/by-id/virtio-disk-drkhklpe /data ext4 defaults 0 0
    • Take automatic mounting using the UUID of the disk partition as an example. Add the following to the previous example:
      UUID=d489ca1c-5057-4536-81cb-ceb2847f9954 /data  ext4 defaults     0   0
    • Take automatic mounting using the device name as an example. Add the following to the previous example:
      /dev/vdb /data   ext4 defaults     0   0
  12. Press Esc, enter :wq, and press Enter.
    Save the configuration and exit the editor.
  13. Execute the following command to check whether the /etc/fstab file has been written successfully.
    mount -a 
    If the command runs successfully, it means the file has been written successfully, and the newly created file system will automatically mount when the operating system is launched.

Creating a file system on a partition

As an example, this article uses the parted partition tool in the CentOS 7.5 operating system to set /dev/vdc data disk as the primary partition, the default partition format is GPT, the file system is set as EXT4 format, mounted under /data/newpart2, and also set to automatically mount at startup. The formatting operations on different operating systems may vary. This article is for reference only.

  1. Log in to the Linux Cloud Virtual Machine.
  2. Execute the following command as the root user to view the disk name.
    lsblk
    Returned information is similar to what is shown in the following figure, which indicates that the current CVM has two disks, “/dev/vda” is the system disk, and “/dev/vdc” is the newly created data disk.
  3. Execute the following command to enter the parted partition tool and execute partitioning operations on the newly added data disk.
    parted <Newly added data disk>
    Take the newly mounted data disk /dev/vdc as an example:
    parted /dev/vdc
    Returned information is similar to what is shown in the following figure:
  4. Enter p, and press Enter to view the current disk partition format.
    Returned information is similar to what is shown in the following figure:

    Partition Table: unknown indicates the disk partition format is unknown.
  5. Execute the following command to set the disk partition format.
    mklabel <Disk partition format>
    If disk capacity is larger than or equal to 2TB, only GPT partition format can be used:
    mklabel gpt
  6. Enter p, and press Enter to view whether the disk partition format has been set successfully.
    Returned information is similar to what is shown in the following figure:

    Partition Table: gpt indicates that the disk partition format is GPT.
  7. Enter unit s and press Enter to set the measurement unit of the disk as sector.
  8. Take creating one partition for the entire disk as an example, enter mkpart opt 2048s 100%, and press Enter.
    2048s indicates the initial disk capacity. 100% indicates the ending disk capacity. This is for reference only. You can plan the number of disk partitions and their capacities according to your business needs.
  9. Enter p and press Enter to view the information of the newly created partitions.
    Returned information is similar to what is shown in the following figure:

    This indicates the detailed information of the newly created partition /dev/vdc1.
  10. Enter q and press Enter to exit the parted partition tool.
  11. Execute the following command to view the disk name.
    lsblk
    Returned information is similar to what is shown in the following figure, you can now see the new partition “/dev/vdc1”.
  12. Execute the following command to set the file system of the newly created partition to the format required by the system.
    mkfs -t <File system format> /dev/vdc1
    The partition size supported by different file systems varies. Select an appropriate file system according to your actual needs. In the following example, EXT4 is set as the file system:
    mkfs -t ext4 /dev/vdc1
    Returned information is similar to what is shown in the following figure:

    The formatting takes a while, please pay attention to the system’s running status, and do not exit.
  13. Execute the following command to create a new mounting point.
    mkdir <Mounting point>
    Take the newly created mounting point /data/newpart2 as an example:
    mkdir /data/newpart2
  14. Execute the following command to mount the newly created partition to the newly created mounting point.
    mount /dev/vdc1 <Mounting point>
    Take the newly created mounting point /data/newpart2 as an example:
    mount /dev/vdc1 /data/newpart2
  15. Execute the following command to view the mounting results.
    df -TH
    Returned information is similar to what is shown in the following figure:

    This indicates that the newly created partition /dev/vdc1 has been mounted to /data/newpart2.

If you do not need to set automatic disk mounting at startup, skip the following steps.

  1. Confirm the mounting method and obtain the corresponding information.
    You can choose to use an elastic cloud disk’s soft link, file system’s UUID (universally unique identifier) or device name to automatically mount a disk, according to your business needs. The related description and information acquisition methods are as follows:
    Mounting method Pros and cons Information acquisition method
    Use the soft link of the elastic cloud disk(Recommended) Pros:The soft link of each elastic cloud disk is fixed and unique, and will not change along with operations such as mounting, unmounting, and formatting partitions.
    Cons:Only elastic cloud disks can use soft links. They cannot sense the formatting operation of the partition.
    Execute the following command to view the soft link of the elastic cloud disk.
    ls -l /dev/disk/by-id
    Use a file system’s UUID Automatic mounting configuration may become invalid due to changes in a file system’s UUID.
    For example, reformatting a file system will change the UUID of the file system.
    Execute the following command to view the UUID of the file system.
    blkid /dev/vdc1
    Use device name Automatic mounting configuration may become invalid due to changes in device name.
    For example, during data migration, the elastic cloud disk on the CVM is unmounted and then remounted. When the operating system recognizes the file system again, the device name may change.
    Execute the following command to view the device name.
    fdisk -l
  2. Backup the /etc/fstab file.
  3. Execute the following command to use VI editor to open the /etc/fstab file.
    vi /etc/fstab
  4. Press i to enter editing mode.
  5. Move the cursor to the end of the file and press Enter, then add the following content.
    <Device information> <Mounting point> <File system format> <File system installation option> <File system dump frequency> <File system check sequence at launch>
    • (Recommended) Take automatic mounting using the soft link of an elastic cloud disk as an example. Add the following to the previous example:
      /dev/disk/by-id/virtio-disk-bm42ztpm-part1 /data/newpart2   ext4 defaults     0   2
    • Take automatic mounting using the UUID of the disk partition as an example. Add the following to the previous example:
      UUID=fc3f42cc-2093-49c7-b4fd-c616ba6165f4 /data/newpart2   ext4 defaults     0   2
    • Take automatic mounting using the device name as an example. Add the following to the previous example:
      /dev/vdc1 /data/newpart2   ext4 defaults     0   2
  6. Press Esc, enter :wq, and press Enter.
    Save the configuration and exit the editor.
  7. Execute the following command to check whether the /etc/fstab file has been written successfully.
    mount -a 
    If the command runs successfully, it means the file has been written successfully, and the newly created file system will automatically mount when the operating system is launched.

Initializing cloud disks (smaller than 2TB).