[CentOS] When should I reboot?

Sat Apr 13 16:25:21 UTC 2019
John R. Dennison <jrd at gerdesas.com>

On Sat, Apr 13, 2019 at 01:32:11AM -0700, Kenneth Porter wrote:
> I reboot when I yum update to a new kernel or systemd, which seems to come
> out about once a month. Should I do it for this week's glibc? Is that "core"
> enough to justify a reboot or should I wait for the next kernel update? I
> know the glibc update was mainly to handle the new Japanese calendar, so
> that shouldn't affect my usage. So my question is more about how shared
> libraries work and whether anything bad would happen with different forks of
> running services (mainly the mail suite with dovecot and the various content
> scanners launched by sendmail) running different versions of the library
> based on when they were started.

As a general rule we recommend that you reboot after updates for the
kernel, glibc, ssh/openssl and systemd due to a lingering bug that
breaks connectivity to dbus.

Rebooting activates the new kernel and as almost all of our kernel
updates are security updates it's quite highly recommended to do so.

systemd has a lingering bug where it loses connectivity to dbus during a
daemon restart and it doesn't get it back.  Rebooting is the only
method (at least that I am aware of) that addresses this.

ssh/openssl are always security updates, you really want to reboot to
ensure everything is running off the new libraries.

We have seen odd issues with glibc updates without reboots that have
cleared up after reboot; from memory I think they were locale issues but
don't quote me on that.  Considering how integral glibc is to the entire
system you are strongly urged to reboot after said updates.

It's like picking a team when you really don't want to root for either

-- Kristin Johnson, 23, on the two political parties, New York Times,
   3 September 2010
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