File Storage NAS:Mount an NFS file system on a Linux ECS instance

Step 1: Install an NFS client

Before you mount an NFS file system on a Linux ECS instance, you must install an NFS client. You need to install the NFS client on each Linux ECS instance only once. You do no need to install the NFS client the next time you mount a file system on the ECS instance.

1. Connect to the ECS instance. For more information, see Connect to an ECS instance.

2. Install an NFS client.

   Operating system	Installation command
   Alibaba Cloud Linux	sudo yum install nfs-utils
   CentOS
   Redhat
   Ubuntu	Run the following installation commands in sequence: sudo apt-get update sudo apt-get install nfs-common
   Debian

3. Optional. Increase the maximum number of concurrent NFS requests that can be sent from an NFS client.

   Run the following commands to set the maximum number of concurrent NFS requests to 128: For more information, see How do I change the maximum number of concurrent NFS requests from an NFS client?

   if (lsmod | grep sunrpc); then
   (modinfo sunrpc | grep tcp_max_slot_table_entries) && sysctl -w sunrpc.tcp_max_slot_table_entries=128
   (modinfo sunrpc | grep tcp_slot_table_entries) && sysctl -w sunrpc.tcp_slot_table_entries=128
   fi
   (modinfo sunrpc | grep tcp_max_slot_table_entries) && echo "options sunrpc tcp_max_slot_table_entries=128" >> /etc/modprobe.d/sunrpc.conf
   (modinfo sunrpc | grep tcp_slot_table_entries) && echo "options sunrpc tcp_slot_table_entries=128" >> /etc/modprobe.d/sunrpc.conf

Step 2: Mount the NFS file system

NFS file systems can be manually or automatically mounted on Linux ECS instances. Manual mounting is suitable for temporary mounting. If you manually mount a NAS file system on an ECS instance, you must remount the file system every time the ECS instance is started or restarted. Automatic mounting is suitable for persistent mounting. If you enable automatic mounting for a NAS file system, you do not need to remount the file system every time the ECS instance is started or restarted. To prevent the mount information from being lost after the ECS instance is restarted, we recommend that you enable automatic mounting for a NAS file system after you manually mount the file system.

Manually mount the NFS file system

You can use the mount target of an NFS file system to mount the file system on a Linux ECS instance.

1. Mount the NFS file system.

   • To mount a General-purpose NAS file system, run one of the following commands.

     Mount a file system by using NFSv3

     sudo mount -t nfs -o vers=3,nolock,proto=tcp,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport file-system-id.region.nas.aliyuncs.com:/ /mnt

     Mount a file system by using NFSv4

     sudo mount -t nfs -o vers=4,minorversion=0,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport file-system-id.region.nas.aliyuncs.com:/ /mnt                                

   • To mount an Extreme NAS file system, run the following command:

     sudo mount -t nfs -o vers=3,nolock,noacl,proto=tcp,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport file-system-id.region.extreme.nas.aliyuncs.com:/share /mnt

   The following table describes the parameters that you can configure in the mount command.

   Parameter	Description
   General-purpose NAS file systems: file-system-id.region.nas.aliyuncs.com:/ /mnt Extreme NAS: file-system-id.region.extreme.nas.aliyuncs.com:/share /mnt	The format is <Domain name of a mount target>:<Name of a shared directory> <Path of a mount directory>. Replace the domain name of a mount target, the name of a shared directory, and the path of a mount directory with the actual values. Domain name of a mount target: To view the domain name, perform the following steps: Log on to the NAS console. On the File System List page, find the file system that you want to manage and click Manage in the Actions column. On the Mount Targets tab, view the domain name of the mount target. For more information, see View the domain name of a mount target. Name of a shared directory: General-purpose NAS file systems: You can enter the root directory / or a subdirectory, for example, /share. If you specify a subdirectory, make sure that the subdirectory exists in the NAS file system. Extreme NAS file systems: The shared directory must start with /share. Example: /share and /share/subdir. If you specify a subdirectory, make sure that the subdirectory exists in the NAS file system. Path of a mount directory: a subdirectory of the Linux ECS instance, for example, /mnt. Make sure that the subdirectory exists. Note We recommend that you specify an empty directory. After a NAS file system is mounted on an ECS instance, the data of the NAS file system is displayed in the mount directory of the ECS instance. If the mount directory is not empty, the local data on the ECS instance is temporarily invisible.
   vers	The protocol version of the file system. vers=3: uses NFSv3 to mount the file system. vers=4: uses NFSv4 to mount the file system. minorversion specifies the minor version number of the protocol. NAS file systems support NFSv4.0. If you use NFSv4 to mount a NAS file system, you must set the minor version number to 0. Note General-purpose NAS file systems support both NFSv3 and NFSv4.0. Extreme NAS file systems support only NFSv3.
   rsize	The size of data blocks that the client can read from the file system. Recommended value: 1048576.
   wsize	The size of data blocks that the client can write to the file system. Recommended value: 1048576.
   hard	If this parameter is not enabled, when File Storage NAS is unavailable, the client may immediately return an error without retrying, which may cause inconsistency or loss of data. We recommend that you enable this parameter.
   timeo	The period of time for which the NFS client waits before the client retries to send a request. Unit: deciseconds (tenths of a second). Recommended value: 600 (60 seconds).
   retrans	The number of times that the NFS client retries to send a request. Recommended value: 2.
   noresvport	Specifies that a new TCP port is used to ensure network continuity between the file system and the ECS instance when the network recovers from a failure. We recommend that you enable this parameter.

   Note

   • If you need to modify the timeo parameter, we recommend that you specify 150 or a greater value. The timeo parameter is measured in deciseconds (tenths of a second). For example, the value 150 indicates 15 seconds.

   • To prevent performance degradation, we recommend that you set both the rsize and wsize parameters to 1048576.

   • The rsize, wsize, hard, timeo, retrans, and noresvport parameters are optional. Separate multiple parameters with commas (,).

   Important

   • To prevent data inconsistency, we recommend that you do not use the soft mount option. If you specify the soft mount option, make sure that you understand the potential risks.

   • We recommend that you do not set any other mount options that are different from the defaults. If you change the read or write buffer sizes or disable attribute caching, the performance may be reduced.

2. Verify the mount result.

   • Command

     mount -l

   • Sample command output

     If a command output that is similar to the following example appears, the mount is successful.

     After the file system is mounted, you can run the df -h command to view the storage capacity of the file system.

   If the file system fails to be mounted, troubleshoot the issue. For more information, see FAQ about troubleshooting of mount failures.

3. After the NAS file system is mounted, you can read data from and write data to the NAS file system on the Linux ECS instance.

   You can access the file system the same way you access a local directory. The following figure shows an example.

(Optional) Automatically mount the NFS file system

You can configure the /etc/fstab file of a Linux ECS instance to automatically mount an NFS file system when the ECS instance is restarted.

1. To mount an Extreme NAS file system, run the following command:

   To mount a General-purpose NAS file system, skip this step and go to Step 2.

   vi /etc/systemd/system/sockets.target.wants/rpcbind.socket

   Open the /etc/systemd/system/sockets.target.wants/rpcbind.socket configuration file, and comment out the rpcbind parameters that are related to IPv6, as shown in the following figure. Otherwise, the rpcbind service fails to run at startup.

   If you want to enable automatic mounting for CentOS 6.x, perform the following steps:

   1. Run the chkconfg netfs on command to enable the netfs service at startup.

   2. Open the /etc/netconfig configuration file and comment out inet6-related information, as shown in the following figure.

2. Open the /etc/fstab configuration file to add mounting configurations.

   General-purpose NAS file system

   • To use NFSv3 to mount the file system, run the following command:

     file-system-id.region.nas.aliyuncs.com:/ /mnt nfs vers=3,nolock,proto=tcp,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,_netdev,noresvport 0 0

   • To use NFSv4 to mount the file system, run the following command:

     file-system-id.region.nas.aliyuncs.com:/ /mnt nfs vers=4,minorversion=0,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,_netdev,noresvport 0 0

   Extreme NAS file system

   file-system-id.region.extreme.nas.aliyuncs.com:/share /mnt nfs vers=3,nolock,noacl,proto=tcp,noresvport,_netdev 0 0

   Note

   If you want to enable automatic mounting for CentOS 6.x, run the chkconfg netfs on command to enable the netfs service at startup.

   For more information, see Mount parameters. The following table describes the parameters that are not included in the preceding table.

   Parameter	Description
   _netdev	Prevents automatic mounting before the network is connected.
   0 (the first value after noresvport)	Specifies whether to back up a file system by running the dump command. A non-zero value indicates that the file system is backed up. For a NAS file system, the default value is 0.
   0 (the second value after noresvport)	The order in which the fsck command checks file systems at startup. For a NAS file system, the default value is 0, which indicates that the fsck command is not run at startup.

3. Run the following command to open the /etc/rc.local file at startup:

   [ !  -f /etc/rc.local ] && echo '#!/bin/bash' > /etc/rc.local; 
   echo "for ((i=1; i<=10; i++)); do if ping -c 1 -W 3 aliyuncs.com; then break; else sleep 1; fi; done" >> /etc/rc.local;
   echo "sleep 3; mount -a -t nfs" >> /etc/rc.local; 
   chmod +x /etc/rc.local

4. Run the reboot command to restart the ECS instance.

   Important

   If you restart the ECS instance, services are interrupted. We recommend that you perform the operation during off-peak hours.

5. Verify that automatic mounting is enabled.

   You can run the df -h command to check the mounted NAS file system within one minute after the ECS instance restarts.

FAQ

• How do I resolve the latency in creating files in an NFS file system?

• How do I resolve the latency in writing data to an NFS file system?

• What can I do if I do not have the permissions to access an NFS file system?

• What do I do if data is not synchronized when I mount an NFS file system on multiple ECS instances?

References

• Mount a file system across VPCs or Alibaba Cloud accounts

• Access file systems in on-premises data centers

• Use POSIX ACLs to control access

• Use NFSv4 ACLs to control access

• Back up files from a General-purpose NAS file system

• Recycle bin