At Thu, 09 Apr 2009 10:38:08 -0500 CentOS mailing list <centos at centos.org> wrote: > > Robert Heller wrote: > > At Thu, 09 Apr 2009 07:49:30 -0400 CentOS mailing list <centos at centos.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. > -- Robert Heller -- 978-544-6933 Deepwoods Software -- Download the Model Railroad System http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows heller at deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/