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The HMC connects to the customer network, and provides access to functions that can be used to manage the DS8900F. Management functions include logical configuration, problem notification, call home for service, remote service, and Copy Services management. 

These Management functions can be performed from the DS8000 Storage Management GUI (DS GUI), DS command-line interface (DS CLI), or other storage management software that supports the DS8900F. 

For example, clients who use an external Copy Services Manager (CSM) for advanced functions, such as Metro Mirror or FlashCopy are communicating to the storage system by connecting the CSM server to the HMCs as management entry point. 

The HMC provides connectivity between the DS8000 and Encryption Key Manager servers (SKLM), if used and also provides the functions for remote call-home and remote support connectivity. 

The HMCs are equipped with Ethernet connections for the client’s network. For more information, see 8.1.3 Private and Management Ethernet networks on page 207. 

To provide continuous availability of access to the management console functions, the DS8900F includes a second management console as default. One HMC takes over the primary and the other MC the secondary role. The role is not determined by the physical position of the HMC and can be chosen at installation time or later on by a customer service representative. using the service management console. However, it is very common that the HMC on the left (when facing the rack) is designated as the primary. 

To set an HMC role, from the Service Console shown in Figure 8-3, select HMC Management →  Query/Activate HMC Role Section 

<img src='content_image/997935.jpg'>

The secondary HMC is now default and it is needed for redundancy reason as example for encryption management or Advanced Copy Services functions. For more information about the secondary HMC, see 8.6 Secondary Management Console on page 229. 

## 8.1.3 Private and Management Ethernet networks 

The HMCs communicate with the storage facility internally through a pair of redundant Ethernet networks, which are designated as the Black Network and the Gray Network. There are two switches which are isolated from each other and they are located in the management enclosure (ME). 

