控制本地名字服务的缓存时间

/usr/sbin/nscd - name service cache daemon

 以及nscd.conf

一个例子

#
# /etc/nscd.conf
#
# An example Name Service Cache config file.  This file is needed by nscd.
#
# Legal entries are:
#
# logfile   <file>
# debug-level  <level>
# threads   <initial #threads to use>
# max-threads  <maximum #threads to use>
# server-user             <user to run server as instead of root>
#  server-user is ignored if nscd is started with -S parameters
#       stat-user               <user who is allowed to request statistics>
# reload-count  unlimited|<number>
# paranoia  <yes|no>
# restart-interval <time in seconds>
#
#       enable-cache  <service> <yes|no>
# positive-time-to-live <service> <time in seconds>
# negative-time-to-live   <service> <time in seconds>
#       suggested-size  <service> <prime number>
# check-files  <service> <yes|no>
# persistent  <service> <yes|no>
# shared   <service> <yes|no>
#
# Currently supported cache names (services): passwd, group, hosts
#

# logfile   /var/log/nscd.log
# threads   6
# max-threads  128
# server-user  nobody
# stat-user  somebody
 debug-level  0
# reload-count  5
 paranoia  no
# restart-interval 3600

 enable-cache  passwd  yes
 positive-time-to-live passwd  600
 negative-time-to-live passwd  20
 suggested-size  passwd  211
 check-files  passwd  yes
 persistent  passwd  yes
 shared   passwd  yes

 enable-cache  group  yes
 positive-time-to-live group  3600
 negative-time-to-live group  60
 suggested-size  group  211
 check-files  group  yes
 persistent  group  yes
 shared   group  yes

# enable-cache  hosts  yes
 enable-cache  hosts  no
 positive-time-to-live hosts  3600
 negative-time-to-live hosts  20
 suggested-size  hosts  211
 check-files  hosts  yes
 persistent  hosts  yes
 shared   hosts  yes
========================================================================

 

 

NSCD.CONF

5

1999-10

GNU C Library

• NAME
  
  /etc/nscd.conf - name service cache daemon configuration file
• DESCRIPTION
  
  The file /etc/nscd.conf is read from nscd(8) at startup. Each line specifies either an attribute and a value, or an attribute, service, and a value. Fields are separated either by SPACE or TAB characters. A `#' (number sign) indicates the beginning of a comment; following characters, up to the end of the line, are not interpreted by nscd.
  
  Valid services are passwd, group, or hosts.
  logfile debug-file-name
  Specifies name of the file to which debug info should be written.
  
  debug-level value
  Sets the desired debug level.
  
  threads number
  This is the number of threads that are started to wait for requests. At least five threads will always be created.
  
  server-user user
  If this option is set, nscd will run as this user and not as root. If a separate cache for every user is used (-S parameter), this option is ignored.
  
  enable-cache service <yes|no>
  Enables or disables the specified service cache.
  
  positive-time-to-live service value
  Sets the TTL (time-to-live) for positive entries (successful queries) in the specified cache for service . Value is in seconds. Larger values increase cache hit rates and reduce mean response times, but increase problems with cache coherence.
  
  negative-time-to-live service value
  Sets the TTL (time-to-live) for negative entries (unsuccessful queries) in the specified cache for service . Value is in seconds. Can result in significant performance improvements if there are several files owned by uids (user IDs) not in system databases (for example untarring the linux kernel sources as root); should be kept small to reduce cache coherency problems.
  
  suggested-size service value
  This is the internal hash table size, value should remain a prime number for optimum efficiency.
  
  check-files service <yes|no>
  Enables or disables checking the file belonging to the specified service for changes. The files are /etc/passwd , /etc/group , and /etc/hosts .
  
  
• SEE ALSO
  
  nscd(8)
• AUTHOR
  
  nscd was written by Thorsten Kukuk and Ulrich Drepper.