Assigning same hostnames for two different servers

Iyyappan · 05-12-2015, 09:35 AM

Hi All,

Application is SAP and DB is Oracle.

We are setting up new servers (with same hostname as the old setup servers) with higher configuration from scratch in the same data center but in a different network.

Once the new server setup are ready, we will scrap old server setup.

During setup there is no issues, but we need to migrate lots of data from old setup servers to the new setup servers.

There is no DNS servers. We have mapped server hostname and IP in hosts file only.

Having said that, during data migration, we need to connect both the network for data transfer.

SAP wise there are some hostname configurations and in DB there is RHEL cluster, which uses hostname.

Will there be any hostname clash when servers from two different networks with same hostname but with different IPs comes in contact.

During data copy we will use only IP and not hostname.

lazydog · 05-12-2015, 10:19 AM

I would not think there would be unless the program you are using to copy files needs the hostname for any reason.

Habitual · 05-12-2015, 10:34 AM

Quote:

Originally Posted by Iyyappan

We have mapped server hostname and IP in hosts file only.
...
SAP wise there are some hostname configurations and in DB there is RHEL cluster, which uses hostname.
...
Will there be any hostname clash when servers from two different networks with same hostname but with different IPs comes in contact.
...
During data copy we will use only IP and not hostname.

Hmmz. "data copy" suggests a mechanism outside of SAP...
Depends on the hostname configurations values in the DB.
The cluster using what I refer to as "Poor Man's DNS" (edits in /etc/hosts) should work.

schneidz · 05-12-2015, 11:18 AM

/etc/hosts seems to ignore the 2nd instance of the same hostname:

Code:

[schneidz@hyper bak]$ cat /etc/hosts
127.0.0.1	localhost.localdomain	localhost
::1	hyper	localhost6.localdomain6	localhost6
192.168.1.105	xbmc
192.168.1.34	mom
192.168.1.114   mom
[schneidz@hyper bak]$ ping -c 5 mom
PING mom (192.168.1.34) 56(84) bytes of data.
64 bytes from mom (192.168.1.34): icmp_req=1 ttl=64 time=0.293 ms
64 bytes from mom (192.168.1.34): icmp_req=2 ttl=64 time=0.203 ms
64 bytes from mom (192.168.1.34): icmp_req=3 ttl=64 time=0.190 ms
64 bytes from mom (192.168.1.34): icmp_req=4 ttl=64 time=0.196 ms
64 bytes from mom (192.168.1.34): icmp_req=5 ttl=64 time=0.490 ms

--- mom ping statistics ---
5 packets transmitted, 5 received, 0 packet loss, time 4000ms
rtt min/avg/max/mdev = 0.190/0.274/0.490/0.115 ms

Iyyappan · 05-13-2015, 12:55 AM

My Setup would be like below

Server A in existing setup
IP - 192.168.1.250
Hostname - prodserv
cat /etc/hosts
192.168.1.250 prodserv

Server A in new setup
IP - 172.19.3.50
Hostname - prodserv
cat /etc/hosts
172.19.3.50 prodserv

During migration time, there will be network connectivity established between 192.168.1.0 and 172.19.3.0 networks.

We will be using scp or rsync only for file transfer.

lazydog · 05-13-2015, 10:48 AM

As long as you use IP Addresses to connect then you should not have an issue.