Bug#998438: Acknowledgement (invalidate caches on package removal)

[Harald Dunkel <harald.dunkel@aixigo.com>]

Control: tag -moreinfo

The caches have to be invalidated before nscd is removed, because
after removing nscd (the binary) you cannot run "nscd -i" anymore.
The cache files have to be removed to make sure that new jobs ignore
the caches completely.

A general problem with nscd is that running jobs continue to use the
caches, even though nscd is gone. Sample:

	# lsof | grep nscd | wc -l
	474
	# systemctl stop nscd
	# lsof | grep nscd | wc -l
	56

See that its not even close to 0? Obviously some jobs didn't
recognize that nscd has been stopped. Running nscd -i and removing
the caches is all the nscd maintainer script could do.

About /run: /var/cache/nscd is appr 1MByte on the hosts I checked.
This is the perfect size to store it RAM. The caches are mapped
into memory, anyway. Please check the output of

	lsof | grep nscd

It says "mem" in the FD column. There is no reason to store the
caches on SSD or rusty disks.


Regards
Harri