[CentOS] updating without rebooting

[m.roth at 5-cent.us]

John R Pierce wrote:
> On 03/25/11 3:15 AM, Fajar Priyanto wrote:
>> Hi all,
>> I'm curious. If I do yum update (which include kernel update) but don't
>> reboot.
>> Is it OK? I mean apart of the kernel, other things like services, we
>> don't have to reboot if we don't have the chance to do it (postponing
>> to some other date), right?
>
> the longer you put off that reboot, the harder it will be to fix if
> something does go wrong, unless you are meticulous about keeping notes
> on each and every change.

Well, within limits. If there's a kernel update that fixes a bug, or
security hole that only affects this NIC, or that OEM hardware bug, and
you don't have either, then it's a moot point. The ones you *really* want
to reboot after are ones that directly affect the hardware and software
you're running, and, if you have users, you want to schedule the reboot
(aka "maintenance window"). The others, we've waited two and three kernels
before we decided to do the reboot. Lessee, 2.6.18-194-11.4, I think, was
important to us, but those since have been no big deal. Most of our
systems have been rebooted to the current kernel, but not all.

(Ah, the joys of getting buyin from the managers of a monthly maintenance
window: no more begging, pleasding, and waiting for days or weeks to do
the reboot, or apache restart, or.... And yes, we are a high perfomance
computing center, and some folks *do* have jobs that run for days or even
weeks....)

          mark "then there are the ones who were antsy about
                   *any* update that might break their
                   (fragile, IMO) packages..."