Help Center/ Dedicated Distributed Storage Service/ User Guide (Paris and Amsterdam Regions)/ Management/ Disk Management/ Expanding the Capacity of a Disk/ Performing Post-Expansion Operations for a Disk in Linux (parted)
Updated on 2022-02-21 GMT+08:00
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Performing Post-Expansion Operations for a Disk in Linux (parted)

Scenarios

In Linux, after the capacity expansion succeeded, the additional disk space needs to be allocated to an existing partition or a new partition.

This topic uses EulerOS 2.0 64bit to describe how to allocate the additional disk space to a partition using parted.

The method for allocating the additional space varies depending on the server OS. This document is used for reference only. For the detailed operations and differences, see the corresponding OS documents.

Based on your service requirements and disk condition, you can choose either of the following ways to allocate the additional disk space:
  • Create a new partition (services will not be interrupted).

    Creating a new partition after expansion does not require the original partitions to be unmounted. Therefore, the impacts on services are minor than expanding an existing partition. This method is recommended for system disks or disks carrying services that cannot be interrupted.

    If the MBR partition style is used, ensure that the disk capacity does not exceed 2 TB and the number of partitions does not reach the upper limit after the expansion.

  • Expand an existing partition (services will be interrupted).

    If the MBR partition style is used and the number of partitions has reached the upper limit, you can only allocate the additional space to an existing partition. Expanding an existing partition does not delete its data, but requires the partition to unmount. Therefore, services will be interrupted.

    If the MBR partition style is used and the disk capacity after expansion will exceed 2 TB, the space exceeding 2 TB cannot be used. To make use of that space, change the disk partition style from MBR to GPT. Data on the disk will be cleared during such a change. Therefore, back up the disk data before changing the partition style.

    Performing the expansion operations with caution. Misoperation may lead to data loss or exceptions. Therefore, you are advised to use CBR to back up the disk data before expansion. For details, see Managing a Backup.

Prerequisites

  • You have logged in to the server.
    • For how to log in to an ECS, see the Elastic Cloud Server User Guide.
    • For how to log in to a BMS, see the Bare Metal Server User Guide.
  • You have attached the disk to the server, and the additional space has not been allocated.

Viewing the Partition Style

Before allocating the additional space, query the current disk partition style. If MBR is used, you can use either the fdisk or parted partitioning tool. If GPT is used, you must use the parted partitioning tool.

  1. Run the following command to view the disk information:

    lsblk

    Information similar to the following is displayed: 
    [root@ecs-1120 linux]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   40G  0 disk 
└─xvda1 202:1    0   40G  0 part /
xvdb    202:16   0  150G  0 disk 
├─xvdb1 202:17   0  100G  0 part /mnt/sdc
└─xvdb2 202:18   0   50G  0 part /mnt/opt
xvdc    202:32   0   40G  0 disk 
├─xvdc1 202:33   0    8G  0 part 
└─xvdc2 202:34   0   32G  0 part

  2. Run the following command and enter p to view the current disk partition style:

    parted Disk name

    For example, run the following command to view the partition style of the /dev/xvdb disk:

    parted /dev/xvdb

    Information similar to the following is displayed: 
    root@ecs-1120 linux]# parted /dev/xvdb
GNU Parted 3.1
Using /dev/xvdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p                                                                
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 161GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End    Size    File system  Name  Flags
 1      17.4kB  107GB  107GB   ext4         opt
 2      107GB   161GB  53.7GB  ext4         opt1

    In the command output, parameter Partition Table indicates the disk partition style. Value msdos indicates the MBR partition style, and value gpt indicates the GPT partition style.

  3. Enter q and press Enter to exit parted.
  4. Check the disk partition style of other disks. For details, see 2 to 3.

Creating a New Partition

The following example shows you how to make use of the additional space of a system disk by creating a new partition and mount the partition on /opt without interrupting services.

  1. Run the following command to view the disk partition information:

    lsblk

    Information similar to the following is displayed: 
    [root@ecs-1120 linux]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   80G  0 disk 
└─xvda1 202:1    0   40G  0 part /
xvdb    202:16   0  250G  0 disk 
├─xvdb1 202:17   0  100G  0 part 
└─xvdb2 202:18   0   50G  0 part 
xvdc    202:32   0   40G  0 disk 
├─xvdc1 202:33   0    8G  0 part 
└─xvdc2 202:34   0   32G  0 part

    In the command output, the capacity of the dev/xvda system disk is 80 GB, in which the in-use dev/xvda1 partition takes 40 GB and the additional 40 GB has not been allocated.

  2. Run the following command to enter parted to allocate the additional space of the system disk to a partition:

    parted System disk

    In this example, run the following command:

    parted /dev/xvda

    Information similar to the following is displayed:

    [root@ecs-1120 linux]# parted /dev/xvda
GNU Parted 3.1
Using /dev/xvda
Welcome to GNU Parted! Type 'help' to view a list of commands.

  3. Enter unit s and press Enter to set the measurement unit of the disk to sector.
  4. Enter p and press Enter to view the current disk partition style.

    Information similar to the following is displayed:

    (parted) unit s                                                   
(parted) p                                                        
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvda: 167772160s
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start  End        Size       Type     File system  Flags
 1      2048s  83886079s  83884032s  primary  ext4

  5. Enter mkpart and press Enter to create a new partition.
  6. In this example, a primary partition is created. Therefore, enter p and press Enter to create a primary partition.

    Information similar to the following is displayed:

    (parted) mkpart
Partition type?  primary/extended? p
File system type?  [ext2]? ext4                                   
Start? 83886080
End? 1677722159

  7. Set the file system type and size for the new partition.

    Value 83886080 indicates the start sector of the dev/xvda2 partition you created, and value 167772159 indicates the end sector. The two values are used for reference only. You can determine the number of partitions and partition sizes based on your service requirements.

    Information similar to the following is displayed:

    (parted) mkpart
Partition type?  primary/extended? p
File system type?  [ext2]? ext4                                   
Start? 83886080
End? 1677722159

    The file system type may fail to set in this step. Therefore, reconfigure the file system type according to 10 after the partition is created.

    The maximum sector can be obtained in either of the following ways:

    • Run the fdisk -l command and take note of the value.
    • Enter -1s, and the value displayed is the desired value.

  8. Enter p and press Enter to view the new partition.

    Information similar to the following is displayed: 
    (parted) p                                                        
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvda: 167772160s
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start      End         Size       Type     File system  Flags
 1      2048s      83886079s   83884032s  primary  ext4
 2      83886080s  167772159s  83886080s  primary

    The dev/xvda2 partition is created.

  9. Enter q and press Enter to exit parted.
  10. Run the following command to set the file system format for the new partition:

    (The ext4 file system is used in this example.)

    mkfs -t ext4 /dev/xvda2

    The procedure for setting the xfs file system is the same as that for the ext3 or ext4 file system. The command for creating the xfs file system is mkfs -t xfs /dev/xvda2.

    Information similar to the following is displayed:

    [[root@ecs-1120 linux]# mkfs -t ext4 /dev/xvda2
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, 10485760 blocks
524288 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

    The formatting takes a while, and you need to observe the system running status. Once done is displayed in the command output, the formatting is complete.

  11. Run the following command to mount the new partition on a space-demanding directory, for example /opt:

    mount /dev/xvda6 /opt

    Information similar to the following is displayed:

    [root@ecs-1120 linux]# mount /dev/xvda2 /opt
[root@ecs-1120 linux]#

    If the new partition is mounted on a directory that is not empty, the subdirectories and files in the directory will be hidden. Therefore, you are advised to mount the new partition on an empty directory or a new directory. If the new partition must be mounted on a directory that is not empty, move the subdirectories and files in this directory to another directory temporarily. After the partition is successfully mounted, move the subdirectories and files back.

  12. Run the following command to view the mount result:

    df -TH

    Information similar to the following is displayed:

    [root@ecs-1120 linux]# df -TH
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/xvda1     ext4       43G  8.3G   33G  21% /
devtmpfs       devtmpfs  885M     0  885M   0% /dev
tmpfs          tmpfs     894M     0  894M   0% /dev/shm
tmpfs          tmpfs     894M   18M  877M   2% /run
tmpfs          tmpfs     894M     0  894M   0% /sys/fs/cgroup
tmpfs          tmpfs     179M     0  179M   0% /run/user/2000
tmpfs          tmpfs     179M     0  179M   0% /run/user/0
tmpfs          tmpfs     179M     0  179M   0% /run/user/1001
/dev/xvda2     ext4       43G   51M   40G   1% /opt

Expanding an Existing Partition

The following example shows you how to make use of the additional space of a disk attached to a server by recreating the /dev/xvdc1 partition mounted on /mnt/sdc. Because the /dev/xvdc disk only has one partition, this partition is regarded as the partition at the disk end. During the partition recreation, services will be interrupted.

During an expansion, the additional space is added to the end of the disk. When the disk has multiple partitions, only the partition at the end of this disk can be expanded.

  1. Run the following command to view the disk partition information:

    lsblk

    Information similar to the following is displayed: 
    [root@ecs-1120 sdc]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   80G  0 disk 
├─xvda1 202:1    0   40G  0 part /
└─xvda2 202:2    0   40G  0 part /opt
xvdb    202:16   0  350G  0 disk 
├─xvdb1 202:17   0  100G  0 part 
└─xvdb2 202:18   0  200G  0 part
xvdc    202:32   0   60G  0 disk 
└─xvdc1 202:33   0    10G  0 part /mnt/sdc

    In the command output, the total capacity of the /dev/xvdc disk is 60 GB, in which the existing partition takes 10 GB. The /dev/xvdc1 partition is at the end of the disk and has been mounted on /mnt/sdc.

    View the /dev/xvdc capacity and check whether the additional space is included.

  2. Run the following command to unmount the partition:

    umount /mnt/sdc

  3. Run the following command to view the unmount result:

    lsblk

    Information similar to the following is displayed: 
    [root@ecs-1120 linux]# umount /mnt/sdc
[root@ecs-1120 linux]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   80G  0 disk 
├─xvda1 202:1    0   40G  0 part /
└─xvda2 202:2    0   40G  0 part /opt
xvdb    202:16   0  350G  0 disk 
├─xvdb1 202:17   0  100G  0 part 
└─xvdb2 202:18   0  200G  0 part
xvdc    202:32   0   60G  0 disk 
└─xvdc1 202:33   0    10G  0 part

  4. Run the following command to enter parted to allocate the additional space of the data disk to a partition:

    parted Data disk

    In this example, run the following command:

    parted /dev/xvdc

    Information similar to the following is displayed: 
    [root@ecs-1120 linux]# parted /dev/xvdc
GNU Parted 3.1
Using /dev/xvdc
Welcome to GNU Parted! Type 'help' to view a list of commands.

  5. Enter unit s and press Enter to set the measurement unit of the disk to sector.
  6. In this example, a primary partition is created. Therefore, enter p and press Enter to create a primary partition.

    Information similar to the following is displayed:

    (parted) mkpart
Partition type?  primary/extended? p
File system type?  [ext2]? ext4                                   
Start? 83886080
End? 1677722159

  7. The /dev/xvdc1 partition number is 1. Therefore, enter rm 1 and press Enter to delete the partition.
  8. Enter p and press Enter to check whether the /dev/xvdc1 partition has been deleted.

    Information similar to the following is displayed: 
    (parted) rm 1
(parted) p                                                                
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdc: 125829120s
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start  End         Size        File system  Name  Flags

  9. Enter mkpart opt 2048s 125829119 and press Enter to recreate the partition.

    2048 specifies the start sector recorded in 6, and 125829119 specifies the end sector, which must be greater than or equal to the end sector recorded in 6.

    Information similar to the following is displayed: 
    (parted) mkpart opt 2048s 125829119s
Warning: You requested a partition from 2048s to 125829199s (sectors 2048..125829199).
The closest location we can manage is 2048s to 125829036s (sectors 2048..125829036).
Is this still acceptable to you?
Yes/No? Yes

    Enter Yes as prompted to set the end sector.

    If the following warning message is displayed, enter Ignore to ignore the performance warning. The warning message will not be displayed if the start sector with the best disk performance has been entered. In this example, 2048s is one of such start sectors. Therefore, the system does not display the warning message. 
    Warning: The resulting partition is not properly aligned for best performance.
Ignore/Cancel? Ignore
    Data will be lost if the following operations are performed:
    • Select a start sector other than the partition had before.
    • Select an end sector smaller than the partition had before.

  10. Enter p and press Enter to check whether the /dev/xvdc1 partition has been recreated.

    Information similar to the following is displayed: 
    (parted) p                                                                
Model: Xen Virtual Block Device (xvd)
Disk /dev/xvdb: 125829120s
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start       End         Size        File system  Name  Flags
 1      2048s       125829086s  125827039s  ext4         opt

    The /dev/xvdc1 partition has been recreated.

  11. Enter q and press Enter to exit parted.
  12. Perform the following operations based on the file system of the disk:

    • For the ext3 or ext4 file system
      1. Run the following command to check the correctness of the file system on /dev/xvdc1:

        e2fsck -f /dev/xvdc1

        Information similar to the following is displayed: 
        [root@ecs-1120 linux]# e2fsck -f /dev/xvdb2
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/xvdc1: 11/655360 files (0.0% non-contiguous), 83137/2620928 blocks
      2. Run the following command to extend the size of the file system on /dev/xvdc1:

        resize2fs /dev/xvdc1

        Information similar to the following is displayed: 
        [root@ecs-1120 linux]# resize2fs /dev/xvdc1
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/xvdc1 to 15728379 (4k) blocks.
The filesystem on /dev/xvdc1 is now 15728379 blocks long.
      3. Run the following command to view the disk partition information after the partition recreation:

        lsblk

        Information similar to the following is displayed: 
        [root@ecs-1120 linux]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   80G  0 disk 
├─xvda1 202:1    0   40G  0 part /
└─xvda2 202:2    0   40G  0 part /opt
xvdb    202:16   0  350G  0 disk 
├─xvdb1 202:17   0  100G  0 part 
└─xvdb2 202:18   0  200G  0 part
xvdc    202:32   0   60G  0 disk 
└─xvdc1 202:33   0    60G  0 part

        In the command output, the total capacity of the /dev/xvdc disk is 60 GB, in which the additional 50 GB has been allocated to the dev/xvdc1 partition.

      4. Run the following command to mount the new partition on /mnt/sdc:

        mount /dev/xvdc1 /mnt/sdc

    • For the xfs file system
      1. Run the following command to mount the new partition on /mnt/sdc:

        mount /dev/xvdc1 /mnt/sdc

      2. Run the following command to extend the size of the file system on /dev/xvdc1:

        sudo xfs_growfs /dev/xvdc1

      3. Run the following command to view the disk partition information after the partition recreation:

        lsblk

        Information similar to the following is displayed: 
        [root@ecs-1120 linux]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   80G  0 disk 
├─xvda1 202:1    0   40G  0 part /
└─xvda2 202:2    0   40G  0 part /opt
xvdb    202:16   0  350G  0 disk 
├─xvdb1 202:17   0  100G  0 part 
└─xvdb2 202:18   0  200G  0 part
xvdc    202:32   0   60G  0 disk 
└─xvdc1 202:33   0    60G  0 part

        In the command output, the total capacity of the /dev/xvdc disk is 60 GB, in which the additional 50 GB has been allocated to the dev/xvdc1 partition.

  13. Run the following command to view the mount result:

    df -TH

    Information similar to the following is displayed: 
    [root@ecs-1120 linux]# mount /dev/xvdc1 /mnt/sdc
[root@ecs-1120 linux]# df -TH
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/xvda1     ext4       43G  8.3G   33G  21% /
devtmpfs       devtmpfs  885M     0  885M   0% /dev
tmpfs          tmpfs     894M     0  894M   0% /dev/shm
tmpfs          tmpfs     894M   18M  877M   2% /run
tmpfs          tmpfs     894M     0  894M   0% /sys/fs/cgroup
tmpfs          tmpfs     179M     0  179M   0% /run/user/2000
tmpfs          tmpfs     179M     0  179M   0% /run/user/0
tmpfs          tmpfs     179M     0  179M   0% /run/user/1001
/dev/xvda2     ext4       43G   51M   40G   1% /opt
/dev/xvdc1     ext4       64G   55M   60G   1% /mnt/sdc

    The /dev/xvdc1 partition has been mounted on the /mnt/sdc directory.

Setting Automatic Mounting at System Start

To automatically mount partitions at system starts, do not specify partitions, for example, /dev/xvdb1, in /etc/fstab because the sequence of cloud devices, and therefore their names may change during the server stop or start. You are advised to use the UUID in /etc/fstab to set automatic mounting at system start.

UUID is the unique character string for disk partitions in a Linux system.

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

    blkid Disk partition

    For example, run the following command to query the UUID of the /dev/xvdb1 partition:

    blkid /dev/xvdb1

    Information similar to the following is displayed:

    [root@ecs-b656 test]# blkid /dev/xvdb1
/dev/xvdb1: UUID="1851e23f-1c57-40ab-86bb-5fc5fc606ffa" TYPE="ext4"

    The UUID of the /dev/xvdb1 partition is displayed.

  2. Run the following command to open the fstab file using the vi editor:

    vi /etc/fstab

  3. Press i to enter the editing mode.
  4. Move the cursor to the end of the file and press Enter. Then, add the following information: 

    UUID=1851e23f-1c57-40ab-86bb-5fc5fc606ffa /mnt/sdc      ext3 defaults     0   2
    UUID=1851e23f-1c57-40ab-86bb-5fc5fc606ffa /mnt/sdc      ext4 defaults     0   2

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

    The system saves the configurations and exits the vi editor.