GLYPH<SM590000> Chosen replication mode 

GLYPH<SM590000> Defined number of concurrent copy tasks 

GLYPH<SM590000> Number of remote write/read operations 

GLYPH<SM590000> Cloud attach configuration 

GLYPH<SM590000> DS8000 Object Store configuration 

Cache bandwidth is always an influencing factor and was described in 12.6, “Cache throughput and cache bandwidth” on page 718. 

## 12.7.1 Mixing different grid link adapters and traffic from Cloud attach or DS8000 object store considerations 

Different grid link adapter types cannot be included in a single cluster. However, a situation can exist in a grid in which some clusters are connected to the grid link by using 10 GB adapters, and other clusters are connected by using 1 GB adapters. This situation is especially true for migration or upgrade scenarios. 

In the TS7700 grid, a 1:1 relationship exists between the primary and primary adapters, and the secondary and secondary adapters. Because of this relationship, in a mixed environment of 2*10 GB and 4*1 GB adapters, the clusters with the 4*1 GB links cannot use the full speed of the installed grid link adapters. 

In the current TS7700C configuration, grid link adapters are shared by communication traffic between clusters and  between a cluster and cloud. When cloud traffic is high (especially in on-premises Object Storage), grid link adapters are highly used. This issue might affect the grid link data replication throughput between clusters in the grid. 

Also, if you configure DS8000 Object Store function that connects to DS8000, data traffic between DS8000 and TS7700 might affect the grid link data replication throughput. Therefore, carefully plan to fit the performance requirements. You can control DFSMShsm data migration from DS8000 to TS7700 by setting the migration schedule in the z/OS side to avoid the grid link adapter competition between usual tape I/O and object store traffic. 

## 12.7.2 Bandwidth and quality of the provided network 

The network between the TS7700s must have sufficient bandwidth to account for the total replication traffic. If you are sharing network switches among multiple TS7700 paths or with other network traffic, the total bandwidth on that network must be sufficient to account for all of the network traffic. 

The TS7700 uses the TCP/IP protocol for moving data between each cluster. In addition to the bandwidth, other key factors affect the throughput that the TS7700 can achieve. The following factors directly affect performance: 

GLYPH<SM590000> Latency between the TS7700s 

GLYPH<SM590000> Network efficiency (packet loss, packet sequencing, and bit error rates) 

GLYPH<SM590000> Network switch capabilities 

GLYPH<SM590000> Flow control to pace the data from the TS7700s 

GLYPH<SM590000> Inter-switch link (ISL) capabilities, such as flow control, buffering, and performance 

GLYPH<SM590000> Network traffic quality of service (QoS) capabilities 

The TS7700s attempt to drive the network links at the full 1-Gb rate for the two or four 1-Gbps links, or at the highest possible load at the two 10-Gbps links, which might be much higher than the network infrastructure can handle. The TS7700 supports the IP flow control frames to have the network pace the rate at which the TS7700 attempts to drive the network. 

