White Papers

Dell HPC NFS Storage Solution High Availability Configurations with Large Capacities

A.4. Performance tuning on the server

All the operations below apply to each R710.

1. If the clients access the NFS server via 10GbE, configure the MTU on the 10GbE device to be 8192

for both the active and the passive server. Note that the switches need to be configured to support

large MTU as well.

On the server, if the value of MTU is not specified in /etc/sysconfig/network-scripts/ifcfg-p2p1,

# echo “MTU=8192” >> /etc/sysconfig/network-scripts/ifcfg-p2p1

change the old value to 8192 in /etc/sysconfig/network-scripts/ifcfg-p2p1.

where ifcfg-p2p1 is the 10GbE network interface.

Restart the networking services.

# service network restart

2. On both the active and the passive server, change the number of NFS threads from a default of 8 to

256.

Make a backup of /etc/sysconfig/nfs and change the number of threads

# cp /etc/sysconfig/nfs{,.orig}

# sed -i 's/#RPCNFSDCOUNT=8/RPCNFSDCOUNT=256/' /etc/sysconfig/nfs

Restart the NFS service.

# service nfs restart

Reference - DELL™ PowerVault™ MD1200 Performance as a Network File System (NFS) Backend

Storage Solution.

http://i.dell.com/sites/content/business/solutions/whitepapers/en/Documents/hpc-pv-md1200-

nfs.pdf

3. On both the active and the passive server, change the OS I/O scheduler to “deadline”.

To the end of the kernel line in /etc/grub.conf, add elevator=deadline

On both the active and the passive servers, preload the driver to avoid excessive messages at boot

time. Find the kernel line in /etc/grub.conf, and append rdloaddriver=scsi_dh_rdac

A reboot the server is needed for this change to take effect, however DO NOT REBOOT until section

A6 is completed.

4. Due to the performance issues observed with NFSv4, some users may want to use NFSv3 to access

the NSS. Two options are proposed to accomplish such restriction.

One option is to preclude NFS version 4 on each of the NSS servers:

Edit the file /etc/sysconfig/nfs and uncomment the RPCNFSDARGS line below

# Turn off v4 protocol support

RPCNFSDARGS="-N 4"