eNFS User Guide

Introduction

With the rapid growth of unstructured data, NAS becomes the best choice for mass unstructured data storage in scenarios such as data sharing and access, frequent data rewriting, local/remote disaster recovery protection, and data permission/resource control. The NFS protocol is widely used in NAS production services. However, the native NFS client has the following disadvantages in terms of performance and reliability:

One mount point is bound to only one IP address. If the software or hardware of the I/O path is faulty, service I/Os are suspended.
Active-active links cannot be automatically switched over in a three-layer network across clouds.
One mount point is bound to only one IP address. In heavy-load service scenarios, the NFS client performance has bottlenecks.

The eNFS feature enhances the native NFS and uses technologies such as multiple links to solve the above problems, greatly improving service performance and stability. When the mount command is used to mount NFS for sharing, the -o option is used to specify the list of IP addresses of the local host and NFS servers. the eNFS feature creates multiple links based on the IP address list. During file operations, eNFS schedules I/Os to multiple links in round-robin mode for load balancing, improving performance. (The current version supports only NFS V3 load balancing.) If some links are faulty during I/O, eNFS quickly distributes timeout I/Os to available links to prevent service suspension.

Hardware and Software Requirements

The host where the eNFS feature is to be used must meet the following requirements:

CPU architecture: AArch64 or x86_64
OS : openEuler 20.03 LTS SP4

eNFS Configuration

eNFS is an enhanced version of the native NFS. Configure eNFS on the NFS client instead of the NFS server.

Set the parameters in the /etc/enfs/config.ini file.

Path connectivity detection interval
```
path_detect_interval=10
```
The value ranges from 5 to 300, in seconds. The default value is 10.
Path connectivity detection timeout period
If the detection message is not returned within the period, the link status is considered abnormal.
```
path_detect_timeout=10
```
The value ranges from 1 to 60, in seconds. The default value is 10.
Timeout threshold for NFS file operations
If the NFS server does not respond within the period, I/Os are processed using other available links.
```
multipath_timeout=0
```
The value ranges from 0 to 30, in seconds. The default value is 0, indicating that the timeo option specified by the mount command is used instead of the configuration of the eNFS module.
Whether to diable path connectivity detection
```
multipath_disable=0
```
The value can be 0 or 1. The default value is 0, indicating that the eNFS feature is enabled.

eNFS Usage

eNFS is an enhanced version of the native NFS client. The mount command is still used to access the NFS server. To use the eNFS feature, use the -o option to specify the localaddrs and remoteaddrs IP address lists.

If the two parameters are not specified, eNFS is not used. In this case, the functionality is the same as that of the native NFS client.

Command Syntax

mount -t nfs -o [localaddrs=127.17.0.1-127.17.0.4],[remoteaddrs=127.17.0.20-127.17.0.24] 127.17.0.20:/test /mnt/test

Description

Parameter	Mandatory	Description
localaddrs	No	If the NFS client has multiple IP addresses that can be connected to the NFS server, enter this parameter to specify the list of local IP addresses used for NFS mounting. If this parameter is not specified, the OS automatically selects IP addresses. Use hyphens (-) to denote IP address ranges. Use tildes (~) to separate multiple IP addresses. A maximum of eight IP addresses are supported.
remoteaddrs	No	If the NFS server has multiple IP addresses that can be connected to the NFS client, enter this parameter to specify the IP address list of the NFS server for NFS mounting. If this parameter is not specified, the IP address of the NFS server mount point in the `mount` command parameter is used, for example, 127.17.0.20 in the preceding command. Use hyphens (-) to denote IP address ranges. Use tildes (~) to separate multiple IP addresses. A maximum of eight IP addresses are supported. Note: The IP addresses specified by remoteaddrs must belong to the same NFS server or NFS server cluster system.

You can run mount -o remount,[localaddrs=127.17.0.1-127.17.0.4],[remoteaddrs=127.17.0.20-127.17.0.24] to modify the IP address lists.

Viewing the eNFS Link Status

After using mount to mount an NFS file system, you can view the status of multiple links.

Procedure

Run the mount command to view the enfs_info information of each mount point.

 $ mount
 8.47.219.120:/fszhn1 on /mnt/fszhn1 type nfs (rw,relatime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=8.47.219.120,mountvers=3,mountport=2050,mountproto=udp,local_lock=none,addr=8.47.219.120,remoteaddrs=8.47.219.121~8.47.219.122~8.47.219.123~8.47.219.124,enfs_info=8.47.219.120_1)

enfs_info is 8.47.219.120_1.

View the path status and I/O statistics.

(1) View the link status.

cat /proc/enfs/8.47.219.120_1/path

In the preceding command, 8.47.219.120_1 is enfs_info obtained in step 1.

$ cat /proc/enfs/8.47.219.120_1/path
id    local_addr      remote_addr     path_state  xprt_state  
0     8.47.210.220    8.47.219.120    Normal      CONNECTED|BOUND
1     8.47.210.220    8.47.219.121    Normal      CONNECTED|BOUND
2     8.47.210.220    8.47.219.122    Normal      CONNECTED|BOUND
3     8.47.210.220    8.47.219.123    Normal      CONNECTED|BOUND
4     8.47.210.220    8.47.219.124    Normal      CONNECTED|BOUND

Output description

Field	Description
id	Link ID
local_addr	Local IP address in the link
remote_addr	NFS server IP address in the link
path_state	Health status of the link Init: initializing Normal: normal Fault: abnormal
xprt_state	Current status of the link CONNECTED: connected CONNECTING: being established BOUND: ready for I/O receiving and sending

(2) View link I/O statistics.

cat /proc/enfs/8.47.219.120_1/stat

8.47.219.120_1 is enfs_info information.

 $ cat /proc/enfs/8.47.219.120_1/stat
 id    local_addr      remote_addr     r_count               r_rtt                 r_exec                w_count               w_rtt                 w_exec  
 0     8.47.210.220    8.47.219.120    0                     0                     0                     0                     0                     0   
 1     8.47.210.220    8.47.219.121    0                     0                     0                     6                     5                     23  
 2     8.47.210.220    8.47.219.122    0                     0                     0                     7                     6                     17  
 3     8.47.210.220    8.47.219.123    0                     0                     0                     0                     0                     0   
 4     8.47.210.220    8.47.219.124    0                     0                     0                     0                     0                     0