Long delay when doing "ls" on a large NFS mounted directory

This document (7005969) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15

SUSE Linux Enterprise Server 12

SUSE Linux Enterprise Server 11

SUSE Linux Enterprise Server 10

SUSE Linux Enterprise Server 9

Situation

When a SUSE NFS client asks for a directory list (ls) of a NFS mount with a large number of files, there may be a long delay before the listing begins to be displayed.

Resolution

The delay is not being caused directly by NFS, it is actually being caused by certain ls options which are "automatically" in place. In a typical SUSE system, giving the "ls" command actually invokes an alias rather than directly executing the /bin/ls command. Giving the "alias" command will show (among other things):

alias ls='/bin/ls $LS_OPTIONS'

The variable $LS_OPTIONS can be revealed with the command:

env | grep LS_OPTIONS

Which will show:

LS_OPTIONS -A -N --color=tty -T 0

The '--color=tty' part of this causes a large additional need for attributes to be checked, in order to assign / display different colors to different types of files and directories. This adds overhead which slows down local disk listings only a little, but can slow down NFS listings quite significantly.

There are a variety of options to deal with this:

1. If the command /bin/ls is given instead of ls, it will bypass the alias and it's options, and will not experience the delay.

2. LS_OPTIONS can be altered to not seek the color-related attributes. To alter the 'LS_OPTIONS' for all users, directly and permanently, edit the scripts which control this setting in the shell environments. The files which do this are:

/etc/bash.bashrc

/etc/csh.cshrc

/etc/ksh.kshrc (although this file is usually just a symbolic link to 'bash.bashrc')

These scripts conditionally turn on the '--color=tty' part of the 'LS_OPTIONS'. For example, in 'bash.bashrc', the following lines can be found:

if test "${LS_COLORS+empty}" = "${LS_COLORS:+empty}" ; then

LS_OPTIONS=--color=tty

else

LS_OPTIONS=--color=none
fi

Change the '--color=tty' (2nd line) to --color=none. After this, any new bash shell opened will not automatically try to display colors in the directory list, and the delay will not occur.

3. Alternatively, to alter this for one user, edit '/home/%user/.bashrc' and add:

export LS_OPTIONS="-A -N -T 0"

(or whatever options are desired for that user).

Additional Information

In cases of huge amount of files e.g. >10k within one directory the "ls" command also tries to sort and get user names resolved which slows down dramatically.

Following 'ls' command will run without sorting and user name resolution producing single column layout:

ls -f1n <directory>

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.