Managing Objects

MRS contains different types of basic objects as described in Table 1.

**Table 1** MRS basic object overview
Object	Description	Example
Service	Function set that can complete specific business.	KrbServer service and LdapServer service
Service instance	Specific instance of a service, usually called service.	KrbServer service
Service role	Function entity that forms a complete service, usually called role.	KrbServer is composed of the KerberosAdmin role and KerberosServer role.
Role instance	Specific instance of a service role running on a host.	KerberosAdmin that is running on Host2 and KerberosServer that is running on Host3
Host	An ECS running Linux OS.	Host1 to Host5
Rack	Physical entity that contains multiple hosts connecting to the same switch.	Rack1 contains Host1 to Host5.
Cluster	Logical entity that consists of multiple hosts and provides various services.	Cluster names Cluster1 consists of five hosts (Host1 to Host5) and provides services such as KrbServer and LdapServer.