Changing the hostname/IP address¶

Overview¶

This document is intended to describe the steps that must be taken if you need to change your Linux Management Node’s hostname and/or IP address after the cluster is installed and configured by xCAT. This documentation will only cover the changes by xCAT and will not try to cover any other changes by any other tools.

Backup your xCAT data¶

Clean up the database by running tabprune command:

tabprune -a auditlog
tabprune -a eventlog

Now take a snapshot of the Management Node. This will also create a database backup. You can use this data as reference if needed.

xcatsnap -d

Stop xCAT¶

You need to stop the xcat daemon and any other applications that are using the xCAT database on the Management Node and the Service Nodes. To determine your database, run

lsxcatd -a | grep dbengine

To stop xCAT:

service xcatd stop

Stop The Database¶

For all databases except SQlite, you should stop the database. For example

service postgresql stop
service mysqld stop

Change the Management Hostname¶

hostname command
```
hostname <new_MN_name>
```
Update the hostname configuration files:

Add hostname in /etc/hostname

Add HOSTNAME attribute in /etc/sysconfig/network (only for [RHEL])

Update Database Files¶

You need to update the new MN hostname or IP address in several database configuration files.

SQLite¶

Nothing to do.

PostgreSQL¶

Edit /etc/xcat/cfgloc file…

Replace Pg:dbname=xcatdb;host=<old_MN_ip>|xcatadm|xcat20 with Pg:dbname=xcatdb;host=<new_MN_ip>|xcatadm|xcat20.
Edit config database config file /var/lib/pgsql/data/pg_hba.conf…

Replace host all all <old_MN_ip>/32 md5 with host all all <new_MN_ip>/32 md5

MySQL¶

Edit /etc/xcat/cfglooc…

Replace mysql:dbname=xcatdb;host=<old_MN_ip>|xcatadmin|xcat20 with mysql:dbname=xcatdb;host=<new_MN_ip>|xcatadmin|xcat20

Start the database¶

service postgresql start
service mysqld start

Start xCAT

service xcatd start

Verify your new database setup

lsxcatd -a | grep dbengine
tabdump site  # if output exists

Change The Definition In xCAT Database¶

Change the site table master attribute¶

chdef -t site master=<new_MN_ip>

Change all IP address attribute relevant to the MN IP address¶

For example, the old IP address was “10.6.0.1”

Query all the attributes with old address

lsdef -t node -l | grep "10.6.0.1"
  ...
  conserver=10.6.0.1
  conserver=10.6.0.1
  conserver=10.6.0.1
  conserver=10.6.0.1
  nfsserver=10.6.0.1
  servicenode=10.6.0.1
  xcatmaster=10.6.0.1
  kcmdline=quiet repo=http://10.6.0.1/install/rhels6/ppc64/ ks=http://10.6.0.1/install/autoinst
  /slessn ksdevice=d6:92:39:bf:71:05
  nfsserver=10.6.0.1
  servicenode=10.6.0.1
  tftpserver=10.6.0.1
  xcatmaster=10.6.0.1
  servicenode=10.6.0.1
  xcatmaster=10.6.0.1

Looking at the list above, taking conserver as an example, query the nodes with conserver=10.6.0.1:

lsdef -t node -w conserver="10.6.0.1"
  ...
  cn1  (node)
  cn2  (node)
  cn3  (node)
  cn4  (node)

Change the conserver address for nodes cn1,cn2,cn3,cn4

chdef -t node cn1-cn4 conserver=<new_ip_address>

Repeat the same process for the other attributes containing the old IP address.

Change networks table¶

Check your networks table to see if the network definitions are still correct, if not edit accordingly

lsdef -t network -l
chdef -t network <key=value>

Check Result¶

You can check whether all the old address has been changed using

dumpxCATdb -P <new database backup path>
cd <new database backup path>
fgrep "10.6.0.1" *.csv

If the old address still exists in the *.csv file, you can edit this file, then use the following command to restore the records

tabrestore <xxx.csv>

Generate SSL credentials(optional)¶

Use the following command to generate new SSL credentials: xcatconfig -c.

Then update the following in xCAT:

Update the policy table with new management node name and replace:

"1.4","old_MN_name",,,,,,"trusted",,

with:

"1.4","new_MN_name",,,,,,"trusted",,``

Setup up goconserver with new credentials
```
makegocons
```

External DNS Server Changed¶

Update nameserver entries in /etc/resolv.conf

Update nameserver attribute in site table

chdef -t site -o clustersite nameservers="new_ip_address1,new_ip_address2"

Update site forwarders in DB

chdef -t site -o clustersite forwarders="new_ip_address1,new_ip_address2"

Run command makedns -n

Domain Name Changed¶

Change the entries in /etc/hosts.

Change the /etc/resolv.conf, forwarders attribute in site table.

lsdef -t site -o clustersite -i forwarders
chdef -t site -o clustersite forwarders <new list>

Change the domain name in the xCAT database site table.

chdef -t site -o clustersite domain=<new_domainname>

From xCAT 2.8, multiple domains is supported in the cluster. Update the networks table definition.

lsdef -t network -l
chdef -t network -o <network_name> ddnsdomain=<new_domainname1,new_domainname2>

Update the Provision Environment¶

Determine if the Management node is defined in the database, assuming it was done correctly using xcatconfig -m, by running:

lsdef __mgmtnode

If it exists, then use the return name and do the following:

Remove the MN from DNS configuration
makedns -d <old_MN_name>
Remove the MN from the DHCP configuration
makedns -d <old_MN_name>
Remove the MN from the conserver configuration
makedns -d <old_MN_name>
Change the MN name in the xCAT database
chdef -t node -o <old_MN_name> -n <new_MN_name>
Add the new MN to DNS
makedns -n
Add the MN to dhcp
makedhcp -a
Add the MN to goconserver
makegocons

Update the genesis packages¶

Run mknb <arch> after changing the ip of MN.