[CentOS-devel] drbd83 update + no kmod update = broken server

On 9/11/09, Johnny Hughes <johnny at centos.org> wrote:
> On 09/10/2009 10:18 PM, Akemi Yagi wrote:
>> On Thu, Sep 10, 2009 at 8:04 PM, Jerry Amundson <jamundso at gmail.com>
>> wrote:
>>> On 9/10/09, Akemi Yagi <amyagi at gmail.com> wrote:
>>>> I think that kmod-drbd82 could / should have been obsoleted by
>>>> kmod-drbd83.  While they can coexist without any conflict, kmod-drbd82
>>>> is no longer needed once drbd82 is updated to drbd83. So, uninstalling
>>>> kmod-drbd82 would make sense.
>>>
>>> Umm, didn't I just read that you're part of the team which builds the
>>> kmods, so can't you just "make it so"? :-)
>>
>> I am part of the ELRepo team.
>>
>> The drbd kmods are built by the CentOS devs.  So ... I am free to find
>> fault with them.  :-D  :-D
>>
>>> Or, back to my original question, should I create a bug report?
>>
>
> Actually, the reason is that kmods are not built in the same way as
> other packages, they are built buy a stand alone script, that I normally
> do not like to modify specifically for individual packages.
>
> Also, there is NO conflict or problem having both modules installed.
>
> Also, ALSO :D, I published an article on how to upgrade DRBD here:
>
> http://centosnow.blogspot.com/2009/08/drbd-packages-in-centos-4-and-centos-5.html

Good to know. [ btw, typo in 2. s/expect/except/ ]

> So, I do not agree that kmod needs to obsolete the older one.  I think
> that having the older kmod there in case you need to boot into the older
> kernel is not bad.

Fair enough.

> The only reason that you had a problem is that the OLD KMOD did not run.

Ahhh, right. I'm still getting bitten by this problem from April[1]
where kernel-xen installs break kmod's until I erase/install the kmod.

[1] http://lists.centos.org/pipermail/centos-devel/2009-April/004368.html

> I would NEVER, EVER update a DRBD cluster with yum.  You need to
> manipulate heartbeat to keep your services on line while upgrading, etc.
> etc.  I would (and do) want to have the old module installed until
> everything is working on the new module.

All fine if you need heartbeat, and have the time to go through the
12+ steps in your blog.

> Also, I am fairly sure the old module will work with older kernels while
> the new module will work with newer kernels regardless of the drbd82 or
> drbd83 installed (since in CentOS 5, the new module may have requires so
> that it does not work on older kernels).

Yes, I just tested the kmod82/drbd83 combo. There is a warning but it
works fine.

Is using drbd on kernel-xen the difference? I'd guess someone must
test such a use case, right? Or, because I don't use heartbeat, but do
have regular (eg. cron) runs of "yum -y update && reboot" I'm
expecting too much?

I realize that sysadmin solutions are never simple, but this seems to
add complexity where it's not needed.

also looking for one of those rocks,
jerry