Important
Notes: In this topic:
Adding a DataCore Server to a server group
Removing a DataCore Server from a server group
Assigning a server group connection interface for inter-node communications (Connection Interface)
Also see:
Configuring Server Groups for Replication
A server group can consist of up to 64 DataCore Servers. The number of DataCore Servers (nodes) in the configuration is limited by license options.
Servers in the same group will exchange configuration information and most operations can be performed from all servers in the group.
Important
Notes:
o When connecting to a server which is part of a group, the user credentials will be authenticated on each server in the group. Therefore, the same user accounts and passwords (domain or local) must exist on all DataCore Servers in the same server group. If using the local Administrator account, that password must also match on all servers in the group. See Connecting to a Server Group for more important information.
o The DcsAdmin password for the server being added must be identical to the DcsAdmin password being used by all existing DataCore Servers in the server group.
o DataCore Servers
(including Replication partners) and remote management consoles require
functioning name resolution to resolve computer names to IP addresses.
To ensure proper communication and data transfer, each server running
SANsymphony software
must be able to resolve the host names of each DataCore Server
in the server group to which it belongs. If using hosts files, the name
in the file must be identical to the actual computer name, including the
case. See Name Resolution for
important information.
We highly recommend
using host names instead of IP addresses. IP addresses can be determined
from host names regardless of changes to the IP addresses.
o Warning: A server with existing virtual disks or virtual disk templates cannot be added to an existing server group. When a server with an existing configuration is added to a server group, some configuration of the server being added will be deleted, such as hosts, users, ports, tasks and so on.
o When adding a new server to an existing group, always invoke the Add DataCore Server operation from the existing group. (After the new server is added to the group, then activate the license keys for the new server.)
o Servers being added to a server group should be running the same version of SANsymphony software as the existing server group. Running different versions of software on servers in the same server group are not supported. If necessary, upgrade software on servers as appropriate before adding new servers to the group.
o The server being added to the group will have virtualization started automatically.
o The Auto-login iSCSI ports check box on the Add DataCore Server dialog box (used to add a server to an existing server group) enables or disables the automatic login of all iSCSI ports between the server being added and all existing servers in the server group.
· By default auto-login is disabled. Auto-login between all iSCSI ports in large server groups can take a considerable amount of time to complete and may cause a lag in response in the user interface. For best performance in Server Groups with a large number of servers, check the Disable iSCSI auto-login check box
· Auto-login should be disabled in order to selectively login iSCSI ports between servers.
· When auto-login is disabled, iSCSI ports must be performed manually in the iSCSI Initiator Details page. See Configuring iSCSI Connections for more information.
o The connection interface is used to connect to a server group and establishes a TCP session for each DataCore Server. This interface is used for communication between DataCore Servers, replication partnerships, and management consoles. See the Assigning a Server Group Connection Interface section below.
To add a server to the local server group:
1 In the
DataCore Servers Panel,
right-click the server group at the top of the panel and select Add DataCore Server
from the context menu. 
2 In the Add
DataCore Server
dialog box, enter the name or IP address of the server to add.
Name or IP address will be used to connect to the server group and for
communications between DataCore Servers.
Also see Assigning
a Server Group Connection Interface for more information.
3 The Auto-login
iSCSI ports check box enables or disables automatic login of all iSCSI ports
between the new server being added and the existing servers in the server
group. Ensure that the check box is
selected or cleared as desired.
See the important notes above
for more information about auto-login.
4 Click Add to continue. A message will appear in the dialog box that reads Adding server, please wait.... while the server is being added. The box closes when the server has been added.
5 If the server that
was added has existing pools which are marked as foreign,
then import the pools.
(Foreign pools will have a warning icon 
in the DataCore Servers Panel.)
6 If using the replication feature, rename the server group.
After the server is added:
o The server
will be displayed in the DataCore Servers Panel.
o A DataCore Server Details page
is also created for the new server.
A DataCore Server can be removed from the local server group if necessary. Removing the server places the server in its own individual server group.
Important:
o Before a DataCore Server is removed from a server group, the storage sources created from the server to be removed must be split from all multi-copy virtual disks or deleted. Also, if the server is removed and then virtual disks are created on the server, that server cannot be added back to the original server group unless those virtual disks are deleted first.
To remove a DataCore Server from the local server group:
1 In the DataCore Servers Panel, right-click the server that you want to remove and choose Remove DataCore Server.
2 A confirmation message will appear, read the warning. Select the check box and click Yes to continue with the operation.
3 After the server is removed, it will retain the same server group name. Rename the server group if desired.
The connection interface is used to connect to a server group and establishes a TCP session. This interface is used for inter-node communication between DataCore Servers, replication partnerships, and management consoles. See Name Resolution for important information.
The connection interface can be assigned for each DataCore Server. The default setting is All. In this case, the connection is made using the host name and the IP address is resolved by the name service.
A specific IP address can also be assigned for the connection interface.
Important Notes:
o Setting a specific IP address for the connection interface will override name resolution provided by the name service. Before assigning or changing the connection interface, consider any Hosts files that are configured on the DataCore Server and any Firewall or IP routing rules that are set up for IP networks.
o In order to make a network connection using host names, all machines must be able to resolve the host names of DataCore Servers to their IP address. See Name Resolution.
o When a specific IP address is assigned, access will only be allowed on that interface. If the selected IP address changes, the connection will fail. There must be a valid network connection between the specified IP address and the other servers in the local server group, replication partnership or management console or the connection will fail.
o We highly recommend using a connection that is not being used for data traffic. The best practice is to use a dedicated connection and have no port roles assigned to the connection.
To assign a connection interface:
1 In the DataCore Server Details page>Settings tab, click the arrow in the Connection interface box and select the interface to use.
2 Click Apply to make the configuration change. The connection will disconnect briefly and reconnect using the new interface.
To change the IP address of the assigned port:
Follow the steps below when a specific port is assigned as the Connection Interface and the IP address of the assigned port needs to be changed.
1 In DataCore Server Details page>Settings tab, set the connection interface setting to All.
2 Ensure virtual disks are healthy and up-to-date.
3 Change the IP address in the name resolution mechanism that you are using for your network configuration, or in the usual manner.
4 Ensure proper name resolution exists between each DataCore Server in the server group, remote management consoles.
5 If necessary, re-assign the new IP address for the connection interface. The connection will disconnect briefly and reconnect using the new interface.
6 Check to be sure that all other DataCore Servers, remote management consoles, and replication partners can access the server with the new IP address.
When replicating virtual disks between two server groups, it is important to rename the server groups to make them unique.
To change server group name:
1 In the
DataCore Servers Panel,
right-click Server Group in the
tree and select Rename.
2 The server group name in the panel becomes a field which you can customize. Enter the new name.
