This section uses CentOS 7.0 (64 bits) to describe how to initialize a data disk mounted to an ECS running Linux.

Viewing a Newly Added Data Disk

Execute the command fdisk -l to view a newly added data disk. Echo is as follows:

The ECS contains two disks. /dev/xvda is the system disk, and /dev/xvdb is the new data disk.

Creating a Partition for the Data Disk

To create a GPT partition for the data disk, refer to Create a GPT Partition.

To create a MBR partition for the data disk, refer to Create a MBR Partition.

Creating a GPT Partition

The following describes how to use the parted tool to create a GPT partition for the new data disk /dev/xvdb .

1.Execute the command parted /dev/xvdb to start the parted partitioning tool. Echo is as follows:

[root@ecs-test]# parted /dev/xvdb
GNU Parted 3.1
Using /dev/xvdb 
Welcome to GNU Parted! Type 'help' to   view a list of commands.

Enter p and press Enter to view the current disk partition form. Echo is as follows:

(parted) p
Error: /dev/xvdb: unrecognised disk label
Model: Xen Virtual Block Device (xvd)                                      
Disk /dev/xvdb: 10.7GB 
Sector size (logical/physical):   512B/512B 
Partition Table: unknown 
Disk Flags:

If Partition Table is unknown , the disk has an unknown partition form.

3.Enter the mklabel gpt command to set the disk partition form. There are two disk partition forms, namely, MBR and GPT. In this example, GPT is used.

4.Enter p and press Enter . Set and check the partition form. Echo is as follows:

(parted) mklabel gpt                                 
(parted) p                                           
Model: Xen Virtual Block Device (xvd) 
Disk /dev/xvdb: 20971520s 
Sector size (logical/physical): 512B/512B 
Partition Table: gpt 
Disk Flags:  
Number  Start  End  Size  File system  Name  Flags

The Partition Table value is gpt , indicating that the disk partition form is GPT.

5.Enter unit s and press Enter to set the measurement unit of the disk to sector.

6.Enter mkpart opt 2048s 100% and press Enter . 2048s indicates the disk start capacity, and **100%**indicates the disk end capacity. The two values are used for reference only. In this example, a partition is created for the entire disk. You can determine the number of partitions and the partition size based on your service requirements. Echo is as follows:

(parted) unit s
(parted) mkpart opt 2048s 100% 
Warning: The resulting partition is not properly aligned for best performance. 
Ignore/Cancel? Ignore

In case of the performance optimization reminder, enter Ignore .

7.Enter p and press Enter to view details about the new partition. Echo is as follows:

(parted) p                                                 
Model: Xen Virtual Block Device (xvd) 
Disk /dev/xvdb: 20971520s 
Sector size (logical/physical): 512B/512B 
Partition Table: gpt 
Disk Flags:  
 Number  Start   End        Size       File system  Name  Flags 
 1      2048s   20969471s  20967424s               opt

8.Enter q and press Enter to exit the parted partitioning tool. A partition is created successfully.

9.Execute the command lsblk to confirm that the partition is successfully created. Echo is as follows:

[root@ecs-test]# lsblk                    
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT 
xvda    202:0    0   40G  0 disk  
├─xvda1 202:1    0    4G  0 part [SWAP] 
└─xvda2 202:2    0   36G  0 part / 
xvdb    202:16   0  100G  0 disk  
└─xvdb1 202:17   0  100G  0 part

Creating a MBR Partition

The following describes how to use the fdisk tool to create an MBR partition for the new data disk /dev/xvdb .

1.Execute the command fdisk /dev/xvdb to start the fdisk partition tool. Echo is as follows:

[root@ecs-test]# fdisk /dev/xvdb 
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 0xb00005bd. 
Command (m for help):

2.Enter n and press Enter to create a partition. Echo is as follows:

Command (m for help): n 
Partition type: 
   p   primary (0 primary, 0 extended, 4 free) 
   e   extended

There are two partition types for a disk: p indicates a primary partition and e indicates an extended partition.

3.In this example, a primary partition is created. Therefore, enter p and press Enter to create a primary partition. Echo is as follows:

Select (default p): p 
Partition number (1-4, default 1):

Partition number indicates the serial number of the primary partition. The value ranges from 1 to

4.Enter the serial number of the primary partition and press Enter . Partition number 1 is used in this example. Echo is as follows:

Partition number (1-4, default 1): 1 
First sector (2048-20971519, default 2048):

First sector indicates the start sector with its value in the range of 2048 - 20971519 , and the default value is 2048 .

5.Select the default start sector 2048 as an example and press Enter . Echo is as follows:

First sector (2048-20971519, default 2048): 
Using default value 2048 
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):

Last sector indicates the end sector with its value in the range of 2048 - 20971519 . The default value is 20971519 .

6.Select the default end sector 20971519 as an example and press Enter. Echo is as follows:

Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): 
Using default value 20971519 
Partition 1 of type Linux and of size 10 GiB is set 
Command (m for help):

It indicates that the partition is created for the 10GB data disk.

7.Enter p and press Enter to view details about the new partition. Echo is as follows:

Command (m for help): p 
 Disk /dev/xvdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0xb00005bd 
    Device Boot      Start         End      Blocks   Id  System 
/dev/xvdb1            2048    20971519    10484736   83  Linux 
 Command (m for help):

8.Enter w and press Enter to write the partition results to the partition table. Echo is as follows:

Command (m for help): w 
The partition table has been altered! 
 Calling ioctl() to re-read partition table. 
Syncing disks.

It indicates that the partition is created successfully.

If there is any mistake in the previous partition operation, enter q to exit the fdisk partition tool. The previous partition results will not be saved.

9.Execute the command partprobe to synchronize the changes of the partition table to the operating system.

Create and Mounr a File System

1.Execute the command mkfs -t ext4 /dev/xvdb1 to create a file system for the new partition. In this example, an ext4 file system is created. Select a proper file system based on your service requirements.

[root@ecs-test]# mkfs -t ext4 /dev/xvdb1 
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 
655360 inodes, 2621184 blocks 
131059 blocks (5.00%) reserved for the super user 
First data block=0 
Maximum filesystem blocks=2151677952 
80 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 
 Allocating group tables: done 
Writing inode tables: done 
Creating journal (32768 blocks): done 
Writing superblocks and filesystem accounting information: done

The formatting takes some time. Observe the system running status and do not exit.

2.Execute the command mkdir /mnt/sdc to create an mounting point. In this example, /mnt/sdc is the mounting point.

3.Execute the command mount /dev/xvdb1 /mnt/sdc to mount the new partition to the new mounting point.

4.Execute the command df -TH to view the mounting result. Echo is as follows:

[root@ecs-test]# df -TH 
Filesystem     Type      Size  Used Avail Use% Mounted on 
/dev/xvda2     xfs        11G  7.4G  3.2G  71% / 
devtmpfs       devtmpfs  4.1G     0  4.1G   0% /dev 
tmpfs          tmpfs     4.1G   82k  4.1G   1% /dev/shm 
tmpfs          tmpfs     4.1G  9.2M  4.1G   1% /run 
tmpfs          tmpfs     4.1G     0  4.1G   0% /sys/fs/cgroup 
/dev/xvda3     xfs       1.1G   39M  1.1G   4% /home 
/dev/xvda1     xfs       1.1G  131M  915M  13% /boot 
/dev/xvdb1     ext4       11G   38M  9.9G   1% /mnt/sdc

It indicates that the new partition /dev/xvdb1 is mounted to**/mnt/sdc**.

Setting Automatic Disk Mounting at Startup

To automatically mount disks at ECS startup, you are advised not to directly specify /dev/xvdb1 in /etc/fstab because a device serial number may change (for example, from /dev/xvdb1 to /dev/xvdb2 ) during the ECS stop or startup. You are advised to use UUID to automatically mount data disks. Universally Unique Identifier (UUID) is the unique character string for disk partitions in a Linux system.

1.Execute the command blkid /dev/xvdb1 to query the partition UUID. Echo is as follows:

[root@ecs-test]# blkid /dev/xvdb1 
/dev/xvdb1: UUID=“******-****-****-****-******” TYPE=“ext4”

2.Execute the command vi /etc/fstab to open the fstab file using the VI editor. Press i to enter the editing mode. Move the cursor to the end of the file and press Enter . Then, add the following information. Enter the UUID queried in the previous step at UUID=.

UUID=******-****-****-****-****** /mnt/sdc      ext4 defaults     0   2

3.Press ESC , enter :wq , and press Enter . Save the settings and exit the editor.

Elastic Volume Service

Initializing a Linux Data Disk