Quickly Buying an EVS Disk and Using It on a Linux Server

Scenarios

EVS disks can be used as system disks or data disks. System disks are purchased together with servers, while data disks can be purchased together with servers or separately. If you buy data disks separately, you must attach and initialize them before they can be used.

This section describes how to buy a non-shared data disk on the EVS console, attach it to a Linux server, and initialize it on the server. Table 1 shows the example configuration.

Operation Process

Making Preparations

1. Register with Huawei Cloud.
   • To sign up a HUAWEI ID and enable Huawei Cloud services, see Registering a HUAWEI ID and Enabling Huawei Cloud Services.
   • To complete real-name authentication, see Individual Real-Name Authentication.
2. Top up your account.
   • To learn more about EVS pricing, see Billing.
   • To top up an account, see Topping Up an Account.
3. Buy a cloud server.
   • For details about how to buy an ECS and use it, see Purchasing and Using an ECS.
   • For details about how to buy a BMS and use it, see Purchasing and Using a BMS.

Step 1: Purchase an EVS Disk

1. Go to the Buy Disk page.
2. Configure mandatory parameters based on Table 2 and retain the default settings for other parameters.
   Figure 1 Configuring parameters
   

   Table 2 Disk creation parameters

   Parameter	Example Value	Description
   Region	CN South-Guangzhou	Resources are region-specific and cannot be used across regions through internal network connections. For low network latency and quick resource access, select the nearest region.
   AZ	AZ1	You can only attach EVS disks to servers in the same AZ. After a disk is created, its AZ cannot be changed.
   	Later	Now: If you select this option, you need to select a server to attach the disk. The billing mode of the disk will be the same as the selected server. Later: When no server is available, you can select this option to create the disk first and attach the disk after the purchase.
   Billing Mode	Pay-per-use	For EVS pricing details, see Billing.
   Data Source	Not configured	If you want to create an empty data disk, do not configure a data source.
   Disk Specifications	Disk type: Ultra-high I/O	To learn more about disk types, see Disk Types and Performance.
   	Capacity: 100 (GiB)	You can only create data disks on the current page. The disk capacity ranges from 10 GiB to 32,768 GiB.
   Disk Name	volume-0001	If you create a single disk, the name you entered will be used as the disk name. The name can contain a maximum of 64 bytes. If you create multiple disks in a batch, the name you entered will be used as the prefix of disk names. An actual disk name will be composed of the name you entered and a four-digit number. The name can contain a maximum of 59 bytes.
   Quantity	1	The preset disk quantity is 1, which means only one disk is created. You can create a maximum of 100 disks at a time.

3. Click Next.
4. Go back to the disk list page. When the status of the volume-0001 disk changes to In-use, the disk is successfully created.

Step 2: Attach the EVS Disk

EVS disks cannot be used alone. You need to attach them to cloud servers first.

1. In the disk list, find the volume-0001 disk and click Attach in the Operation column.
2. Attach the volume-0001 disk to your desired server. Ensure that the server and disk are in the same AZ.
   Figure 2 Attach Disk
   

3. Click OK to go back to the disk list page. When the status of the volume-0001 disk changes to In-use, the disk is successfully attached.

Step 3: Initialize the EVS Disk

After attaching the volume-0001 disk, you need to initialize it before it can be used. The following example uses fdisk to format the disk into two primary MBR partitions, with one 40 GiB and the other 60 GiB.

1. Log in to the server and create two primary partitions, /dev/vdb1 and /dev/vdb2 for data disk /dev/vdb.
   1. Check that the capacity of the /dev/vdb data disk is 100 GiB.
      lsblk

      [root@ecs-centos76 ~]# lsblk
      NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
      vda    253:0    0  40G  0 disk
      ├vda1 253:1    0   1G  0 part /boot
      └vda2 253:2    0  39G  0 part /
      vdb    253:16   0  100G 0 disk

   2. Create the first primary partition /dev/vdb1.

      fdisk /dev/vdb

      n

      p

      [root@ecs-test-0001 ~]# fdisk /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 0x38717fc1.
      
      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

      Entering p for Partition type creates a primary partition, and entering e creates an extended partition.

      Set First sector to 2048 and Last sector to 83886079 for partition /dev/vdb1 (40 GiB).

      First sector (2048-209715199, default 2048): 2048
      Last sector, +sectors or +size{K,M,G} (2048-209715199, default 209715199):83886079
      Partition 1 of type Linux and of size 40 GB is set

   3. Create the second primary partition /dev/vdb2.

      n

      p

      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 2): 2

      Set the First sector to 83886080 and Last sector to 209715199 for partition /dev/vdb2.

      First sector (83886080-209715199, default 83886080): 83886080
      Last sector, +sectors or +size{K,M,G} (83886080-209715199, default 209715199):209715199
      Partition 2 of type Linux and of size 60 GB is set

      

      First and last sectors of the partitions in this example are calculated as follows:

      Sector value = Capacity/512 bytes, 1 GiB = 1073741824 bytes

      • First sector (2048-209715199, default 2048) shows the sector value range of the /dev/vdb data disk (100 GiB).

        First sector = 2048

        Last sector = Sector value – 1 = (100 x 1073741824/512) – 1 = 209715200 – 1=209715199

      • For the first partition /dev/vdb1 (40 GiB) of the /dev/vdb data disk:

        First sector = 2048 (The start sector of the /dev/vdb data disk is used.)

        Last sector = Sector value – 1 = (40 x 1073741824/512) – 1 = 83886079

      • For the second partition /dev/vdb2 (60 GiB) of the /dev/vdb data disk:

        First sector = Last sector of /dev/vdb1 + 1 = 83886079 + 1 = 83886080

        Last sector = First sector + Sector value – 1 = 83886080 + (60 x 1073741824/512) – 1 = 209715199

2. Check the sizes and partition styles of the new partitions.
   1. Check whether the partitioning is successful.
      p

      Command (m for help): p
      
      Disk /dev/vdb: 107.4 GB, 107374182400 bytes, 209715200 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: 0x994727e5
      
         Device Boot       Start         End      Blocks   Id  System
      /dev/vdb1             2048    83886079    41942016   83  Linux
      /dev/vdb2         83886080   209715199    62914560   83  Linux
      
      Command (m for help):

      

      In case that you want to discard the changes made before, you can exit fdisk by entering q and press Enter. Then, re-create the partitions by referring to step 1.

   2. Write the changes to the partition table and synchronize the new partition table to the OS.

      w

      partprobe

      

      If error message -bash: partprobe: command not found is returned, the system cannot identify the command. In this case, run yum install -y parted to install the command. Then run the command again.

   3. Confirm that the partition style is MBR.

      parted /dev/vdb

      p

      [root@ecs-test-0001 ~]# parted /dev/vdb
      GNU Parted 3.1
      Using /dev/vdb
      Welcome to GNU Parted! Type 'help' to view a list of commands.
      (parted) p
      Model: Virtio Block Device (virtblk)
      Disk /dev/vdb: 107GB
      Sector size (logical/physical): 512B/512B
      Partition Table: msdos
      Disk Flags:
      
      Number  Start   End      Size     Type     File system  Flags
       1      1049kB  42.9GB   42.9GB   primary
       2      42.9GB  107GB    64.4GB   primary             
      
      (parted) q
      [root@ecs-test-0001 ~]# 

      If Partition Table: msdos is returned, the partition style is MBR.

      Enter q and press Enter to exit parted.

3. Create ext4 file systems for partitions /dev/vdb1 (40 GiB) and /dev/vdb2 (60 GiB).

   mkfs -t ext4 /dev/vdb1

   mkfs -t ext4 /dev/vdb2

   

   It takes some time to create file systems. Do not exit before the system returns the following information:

   [root@ecs-test-0001 ~]# mkfs -t 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
   2621440 inodes, 10485504 blocks
   524275 blocks (5.00%) reserved for the super user
   First data block=0
   Maximum filesystem blocks=2157969408
   320 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, 7962624
   
   Allocating group tables: done
   Writing inode tables: done
   Creating journal (32768 blocks): done
   Writing superblocks and filesystem accounting information: done

   Run parted /dev/vdb and enter p to check that the file system format is ext4.

   [root@ecs-test-0001 ~]# parted /dev/vdb
   GNU Parted 3.1
   Using /dev/vdb
   Welcome to GNU Parted! Type 'help' to view a list of commands.
   (parted) p
   Model: Virtio Block Device (virtblk)
   Disk /dev/vdb: 107GB
   Sector size (logical/physical): 512B/512B
   Partition Table: msdos
   Disk Flags:
   
   Number  Start   End      Size     Type     File system  Flags
    1      1049kB  42.9GB   42.9GB   primary  ext4
    2      42.9GB  107GB    64.4GB   primary  ext4            
   
   (parted) q
   [root@ecs-test-0001 ~]#

   Enter q and press Enter to exit parted.

4. Create directories (mount points) and mount the new partitions on the created mount points.

   mkdir -p /mnt/sdc

   mkdir -p /mnt/sdd

   mount /dev/vdb1 /mnt/sdc

   mount /dev/vdb2 /mnt/sdd

   lsblk

   View the mount results.

   [root@ecs-test-0001 ~]# lsblk
   NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
   vda    253:0    0  40G  0 disk
   ├vda1 253:1    0  40G  0 part /
   vdb    253:16   0 100G  0 disk
   ├vdb1 253:17   0  40G  0 part /mnt/sdc
   ├vdb2 253:18   0  60G  0 part /mnt/sdd

   You should now see that partitions /dev/vdb1 and /dev/vdb2 are mounted on /mnt/sdc and /mnt/sdd.

5. Use the partition UUIDs to configure auto mount at startup.
   

   • Mounts become invalid after a system reboot. You can configure auto mount at startup by adding information of the new partition into the /etc/fstab file.
   • You are advised not to use device names to identify disks in the /etc/fstab file because device names are assigned dynamically and may change (for example, from /dev/vdb1 to /dev/vdb2) after a stop or start. This can even prevent your server from booting up.
   • UUIDs are the unique character strings for identifying partitions in Linux.
   • This operation does not affect the existing data on the server.
   1. Query the partition UUIDs.

      blkid /dev/vdb1

      blkid /dev/vdb2

      [root@ecs-test-0001 ~]# blkid /dev/vdb1
      /dev/vdb1: UUID="0b3040e2-1367-4abb-841d-ddb0b92693df" TYPE="ext4"
      /dev/vdb2: UUID="0d6769k2-1745-9dsf-453d-hgd0b34267dj" TYPE="ext4"

      The UUIDs of partitions /dev/vdb1 and /dev/vdb2 are 0b3040e2-1367-4abb-841d-ddb0b92693df and 0d6769k2-1745-9dsf-453d-hgd0b34267dj.

   2. Configure auto mount at startup.

      vi /etc/fstab

      Press i to enter the editing mode, move the cursor to the end of the file, press Enter, and add the following content:

      UUID=0b3040e2-1367-4abb-841d-ddb0b92693df    /mnt/sdc     ext4    defaults     0    2
      UUID=0d6769k2-1745-9dsf-453d-hgd0b34267dj    /mnt/sdd     ext4    defaults     0    2

      Press Esc, enter :wq, and press Enter to save the settings and exit the vi editor.

      Table 3 Parameter description

      Example Value	Description
      UUID=0b3040e2-1367-4abb-841d-ddb0b92693df	The UUID of the partition.
      /mnt/sdc	The mount point of the partition.
      ext4	The file system format of the partition.
      defaults	The partition mount option. Normally, this parameter is set to defaults.
      0	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.
      2	The fsck option, which means whether to use fsck to check the disk during startup. 2: The check starts from the partitions whose mount points are non-root directories. / is the root directory. 1: The check starts from the partitions whose mount points are root directories. 0: The fsck option is not used.

6. Verify that auto mount takes effect.

   umount /dev/vdb1

   umount /dev/vdb2

   mount -a

   The system reloads all the content in the /etc/fstab file.

   Query file system mounting information.

   mount | grep /mnt/sdc

   mount | grep /mnt/sdd

   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)
   root@ecs-test-0001 ~]# mount | grep /mnt/sdd
   /dev/vdb2 on /mnt/sdd type ext4 (rw,relatime,data=ordered)

After initializing the disk, go back to the disk list page. After the disk status changes to In-use, you can use the disk.