Hi Christian,
Thanks for the response. So do I actually have to reinstall the SNs and/or
rerun the service node postscript? If reruning the SN post script just
makes some minor adjustments but doesn't clear the dhcpd.leases and the
.conf files for named and dhcp, as I have them configured, then that would
be fine, but if it blows all that away and starts over that would qualify
as disruptive for my environment since the cluster depends on slave DNS
services and dhcp on the SN. I would ideally like minimal changes on the
SNs except to point them to the new MN.
As far as the postscripts, my question was what common (if not default in
most installs) postscripts that come with xCAT have code in them that would
result in the hardcoding of the MN's IP in some configuration file. I
actually thought of one possible example along those lines, and that is
whatever configures the client compute nodes to send all their syslog
messages to the /var/log/messages log on the headnode instead of locally
will need to be rerun/updated. What will need to be run to change that to
make the clients log to the new MN server?
Regarding the server identity (even though it will have a new IP address
and hostname) can we just copy the keys in /etc/ssh/ to the new MN so that
the SSH fingerprint doesn't change?
Lastly, as regards running updatenode -k I definitely (in this case) do not
want to replace the root rsa_id private and public keys on the cluster, the
MN, or the SNs since other critical services like GPFS require the current
keys to remain in place. Why is rerunning the key deploy necessary and is
there not a way to make it work with the current keys?
I just need to be very careful with my current setup so that I don't knock
out critical services while changing the MN, which is why I was wondering
how disruptive doing this might be. I appreciate the help!
Thanks,
Josh
On Tue, May 3, 2016 at 10:05 AM, Christian Caruthers <[email protected]>
wrote:
> I would begin by looking at the servicenode postscript. It sets up the
> daemon and database communications between SN & MN. Beyond that, the
> default postscripts are listed in the "xcatdefaults" entry of the
> postscripts table. You will probably want to run updatenode -k once you
> have xCAT configured on the new MN. After that, you probably want to rerun
> the remoteshell and syslog postscripts on the cluster members (updatenode
> -P) at the very least.
>
>
>
> Second, you can dump the xCAT DB using dumpxCATdb command. After that,
> grep out the management node (hostname and/or IP) to see where changes need
> to be made for the DB on the new MN.
>
>
>
> If the SNs are handling DHCP, it only needs to be enabled on the MN if you
> plan in reinstaling a SN.
>
>
>
> Anything that resolves DNS through the MN will need an updated resolv.conf.
>
>
>
> Depending on how you're maintaining your /install directory on the SNs,
> that mechanism will need to be updated.
>
>
>
> If your MN is routing for any nodes, that will need to be addressed. You
> might want to check the network configuration on the IMMs. On discovery, if
> you have a gateway defined on your management network (I believe it
> defaults to <xcatmaster>), they might be pointing to the old MN. Shouldn't
> be an issue, but it's something to think about. If you're not routing on
> that network, I would use pasu to set the IMM gateway to 0.0.0.0 and be
> done with it.
>
>
>
> The only other concern I can think of would be the installation repos
> configured on the cluster nodes and SNs. If any point to the MN, they will
> need to be changed.
>
>
>
> Aside from all of that, it really depends on the particulars your cluster.
>
>
>
> Regards,
> *Christian Caruthers*
> Lenovo xESS IT Consultant
>
> Mobile: 757-289-9872
>
>
>
>
>
> *From:* Josh Nielsen [mailto:[email protected]]
> *Sent:* Monday, May 02, 2016 8:32 PM
> *To:* xCAT Users Mailing list
> *Subject:* [xcat-user] How can I migrate to a new xCAT MN in a
> hierarchical environment?
>
>
>
> Hello all,
>
> My team is trying to move the xCAT MN role off of an old server and get it
> over onto new virtual infrastructure, but I am a little unsure about
> whether it is possible to do while leaving everything else in its place as
> we currently have it in our environment. We have an MN with two SNs for our
> xCAT environment, and I would need to make the SNs recognize that the new
> MN (with a new IP and hostname) is now their xcatmaster, and they would
> need to take hierarchical command updates from the new MN, look to the new
> MN for the xCAT database (which is a MySQL database in our environment),
> etc.
>
> So a few questions along those lines.
>
> 1. Which/how many xCAT database fields would I need to update that use the
> MN's IP (other than "master" in the site table), and would I have to
> reinstall or otherwise update anything on the SNs (I imagine restarting the
> daemons is necessary at a minimum) in case they have anything statically
> configured for the current MN's IP?
>
> 2. Do any default postscripts for deployed clients ever place the MN's
> hostname or IP in any config files that would require manual alteration if
> the MN is changed? Our client nodes should, however, have one of the two
> SNs as their designated xcatmaster, instead of the MN, as shown by an
> 'lsdef'.
>
> 3. And as far as DHCP, the MN does not even need DHCP running if the SNs
> are handling DHCP, correct? Would I have to change any of my 'networks'
> table entries and DHCP IP pool config in any case, or should simply dumping
> and importing the current DB settings in to the new MN instance be seamless?
>
> DNS I think (hope) should be an easier matter, since we already have an
> external DNS server configured that the MN pushes entries to with a
> 'makedns -e', so no DNS dependency lies on the present MN itself. I imagine
> I'd have to copy the /etc/hosts from the current MN over to the new though
> for the makedns (and other things) to continue working.
>
> I have attached an image with a simplified sketch of what our xCAT
> environment looks like. Overall I'm just wondering what changes would I
> need to make for this to be possible.
>
> Thanks for your input.
>
> Josh Nielsen
>
>
>
>
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