Prepare the environment

Prerequisites

You have created a project.

Resource planning

For more information about resource planning, see Resource planning.

Create logical volumes

This section describes how to create the /apsara and /apsaradb directories.

Logical Volume Manager (LVM) is a disk management tool for Linux that creates a logical layer over physical disks and partitions to simplify disk management. You can resize logical volumes without losing data. You can also add new disks without changing the existing logical volumes.

This topic describes how to use LVM to create a logical volume on multiple disks. The following example uses two new disks: /dev/vdb and /dev/vdc. The following figure shows the LVM configuration.

The procedure is as follows:

1. Create physical volumes (PVs).

   Create and attach two new disks to the destination instance. Do not format the disks.

   1. Remotely connect to the destination instance.

   2. Run the following command to install the LVM tool.

      sudo yum install -y lvm2

   3. Run the following command to view all disks on the destination instance.

      lsblk

      The following example output shows two disks: vdb and vdc. You can use LVM to create a scalable logical volume.

      

   4. Run the following command to create physical volumes from the disk devices. If you want to specify multiple device names, separate them with spaces.

      sudo pvcreate <device_name> ... <device_name>

      The following example shows how to use the /dev/vdb and /dev/vdc devices to create two physical volumes.

      sudo pvcreate /dev/vdb /dev/vdc

      The following example output indicates that the physical volumes are created.

      

2. Create a volume group (VG).

   1. Run the following command to create a volume group.

      Mount target	Product	Command
      /apsara	General	sudo vgcreate vg_apsara <physical_volume_name> <physical_volume_name> In this topic, the example command is as follows: sudo vgcreate vg_apsara /dev/vdb /dev/vdc
      /apsaradb	PolarDB-X	sudo vgcreate -s 32 vg_apsaradb <physical_volume_name> <physical_volume_name>
      	Others	sudo vgcreate vg_apsaradb <physical_volume_name> <physical_volume_name>

      The following example output indicates that the volume group is created.

      

   2. Run the following command to view information about the volume group.

      sudo vgs

      The following result shows that the vg_apsara volume group is created with a capacity of approximately 999 GB. The file system consumes some storage space.

      

3. Create a logical volume (LV).

   1. Run the following command to create a logical volume.

      Mount target	Product	Command
      /apsara	General	sudo lvcreate -L 768g -n <logical_volume_name> <volume_group_name> In this topic, the example command is as follows: sudo lvcreate -L 768g -n lv_apsara vg_apsara
      /apsaradb	General	sudo lvcreate -A y -I {stripe_size} -l 100%FREE -i {stripe_len} -n lv_apsaradb vg_apsaradb

      When you create /apsaradb, the recommended values for the {stripe_size} and {stripe_len} parameters are as follows:

      Product name	stripe_size	stripe_len
      AnalyticDB for PostgreSQL	64k	Number of available disks
      PolarDB-X	128k	Number of available disks (4 is recommended)
      PolarDB for PostgreSQL	8k	Number of available disks
      Tair	128k	Number of available disks
      Lindorm	128k	Number of available disks
      Default	128k	Number of available disks

      The following example output indicates that the logical volume is created.

      

      

   2. Run the following command to verify that the data striping parameters are correct. The following figure shows that stripe_len is 4 and stripe_size is `128k`.

      sudo lvs -o stripes,stripesize -S "lv_name=lv_apsaradb"

      

4. Create and mount a file system.

   1. Run the following command to obtain information about the logical volume, such as its path, name, and volume group. This information is required for the subsequent steps.

      sudo lvdisplay

      

      • LV Path: The path of the logical volume. Example: /dev/vg_apsara/lv_apsara.

      • LV Name: The name of the logical volume. Example: lv_apsara.

      • VG Name: The name of the volume group to which the logical volume belongs. Example: vg_apsara.

      • LV Size: The size of the logical volume. In the figure, the size is 768 GiB.

   2. Run the following command to create a file system on the logical volume.

      Mount target	Product	Command
      /apsara	General	sudo mkfs.<file_system_format> <logical_volume_path> The following example uses the ext4 file system: sudo mkfs -t ext4 -m 0 -q -J size=4096 -T largefile -i 16384 /dev/vg_apsara/lv_apsara
      /apsaradb	PolarDB-X	sudo mkfs.ext4 /dev/vg_apsaradb/lv_apsaradb -m 0 -O extent,uninit_bg -E lazy_itable_init=1 -q -L apsaradb -J size=4096
      	Others	sudo mkfs -t ext4 -m 0 -q -J size=4096 -T largefile -i 16384 /dev/vg_apsaradb/lv_apsaradb

   3. You can create a new mount target.

      sudo mkdir /apsara
      sudo mkdir /apsaradb

   4. Run the following command to mount the file system to the mount target.

      sudo mount <logical_volume_path> <mount_target>

      The following example shows how to mount the logical volume at the path /dev/vg_apsaradb/lv_apsaradb to the /apsaradb directory.

      sudo mount /dev/vg_apsara/lv_apsara /apsara
      sudo mount /dev/vg_apsaradb/lv_apsaradb /apsaradb

   5. Check the mount result.

      Run the following command to check whether the logical volume is mounted.

      df -h

      The following example output shows that /apsara and /apsaradb are displayed in the Mounted on column. This indicates that the mount is successful and the mount targets meet the requirements. A small amount of space is used because the file system consumes some storage space.

      

5. Configure automatic mounting at startup.

   To automatically mount the logical volume at startup, you must add its mount information to the /etc/fstab file.

   1. Run the following command to back up the /etc/fstab file.

      sudo cp /etc/fstab /etc/fstab.bak

   2. Run the following command to add the mount information of the destination logical volume to the /etc/fstab file.

      Mount target	Product	Command
      /apsara	General	sudo sh -c "echo `blkid <logical_volume_path> | awk '{print $2}' | sed 's/\"//g'` <logical_volume_mount_target> <file_system_type_of_logical_volume> defaults 0 0 >> /etc/fstab" In this topic, the example command is as follows: sudo sh -c "echo `blkid /dev/vg_apsara/lv_apsara | awk '{print $2}' | sed 's/\"//g'` /apsara ext4 defaults 0 0 >> /etc/fstab"
      /apsaradb	PolarDB-X	echo "LABEL=apsaradb /apsaradb ext4 defaults,noatime,data=writeback,nodiratime,nodelalloc,barrier=0 0 0" >> /etc/fstab
      	Others	sudo sh -c "echo `blkid /dev/vg_apsaradb/lv_apsaradb | awk '{print $2}' | sed 's/\"//g'` /apsaradb ext4 defaults 0 0 >> /etc/fstab"

   3. Run the following command to check whether the mount information of the logical volume is added.

      cat /etc/fstab

      The following result shows that the information of the destination logical volume is displayed. This indicates that the mount information is added to the /etc/fstab file.

      

   4. Verify that the automatic mount feature is enabled.

      Run the following command to remount the file systems that are configured in /etc/fstab. If no error is reported, the logical volume is mounted to the specified mount target.

      sudo mount -a

   5. Run the following command to check the device or partition to which the logical volume is mounted.

      df -Th