on 4-9-2009 9:01 AM Robert Heller spake the following:
At Thu, 09 Apr 2009 10:38:08 -0500 CentOS mailing list centos-IFYaIzF+flcdnm+yROfE0A@public.gmane.org wrote:
Robert Heller wrote:
At Thu, 09 Apr 2009 07:49:30 -0400 CentOS mailing list centos-IFYaIzF+flcdnm+yROfE0A@public.gmane.org wrote:
What is the rule of thumb for reboots after updates...
Certainly if I update from 5.2 to 5.3 I reboot.
But if you update something like krb5 or pam does that require a reboot? Does the "fix" get automatically loaded and used or do you just do a reboot always?
You only *really* need to reboot if/when you update the kernel. Yum/RPM takes care of restarting daemons, etc. during the update process. This is NOT MS-Windows....
Yes, but any program that is already running will keep using the old versions of the program, libraries, open files, etc., retaining the disk space and not sharing the in-memory copy with new instances that start after the update. And since modern programs like to dynamically load library modules as needed while running you can get a strange mix of old/new versions running at once.
Generally, this is not as bad as it seems. In some cases, some updates do restart critical daemons (rpm -hUv glibc... will restart sshd for example). Also, since most critical library updates also imply a similar update for the deamons/programs that use those libraries and since the rpms for the deamon programs do restart the deamon they install/update, in most cases the deamons do get restarted at some point during the update process -- that is, since httpd (Apache) depends on apr and when apr gets a critical update, it is very likely that the httpd program would also be rebuilt as well, so that both rpms are updated in the repo. A 'yum update' will install the new apr rpm, then the new httpd rpm and at that point restart httpd, this picking up the new apr library.
Sometimes you just have to know your system. Like if you update a sendmail milter, you would need to restart sendmail also, but if the rpm developer didn't write that into the %post section you would want to do it yourself.