Red Hat Bugzilla – Bug 241945
RHEL 4.4 nscd not (apparently) caching anything
Last modified: 2016-11-24 10:52:02 EST
Description of problem:
nscd does not appear to be caching anything in RHEL 4.4.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.In /etc/nscd.conf, enable logging to /var/log/nscd.log and set debug level to 99
2. Restart nscd
3. Run attched perl script
grep 'GETPWBYNAME' /var/log/nscd.log | wc -l
...will show positive values after running script, however...
The output of 'nscd -g' will show
0% cache hit rate
'nscd -g' should show a 99% (or 100%) cache hit rate
This works fine on RHEL 3
Created attachment 155842 [details]
a script to exercise nscd by repeatedly querying the passwd & group tables
Same results with nscd-2.3.4-2.36 as well.
In RHEL4 nscd.conf defaults to shared yes and persistent yes for all databases.
This means that nscd's cache is read-only mapped in applications and they
search the cache directly instead of asking nscd to do the cache search
for them. Only when a request (or a negative search entry) is not found in
the cache, apps ask nscd over the socket and nscd does the search and adds it to
the cache. nscd -g stats only report requests that actually made it to nscd,
it can't see requests answered just by cache search within the applications.