Chapter 10. Copy services 553
The minimum supported link bandwidth is 10 Mbps.
The inter-cluster heartbeat traffic uses 1 Mbps per link.
Only nodes from two I/O Groups can have ports that are configured for an IP partnership.
Migrations of remote copy relationships directly from FC-based partnerships to IP
partnerships are not supported.
IP partnerships between the two systems can be over IPv4 or IPv6 only, but not both.
Virtual LAN (VLAN) tagging of the IP addresses that are configured for remote copy is
supported starting with V7.4.0.
Management IP and Internet SCSI (iSCSI) IP on the same port can be in a different
network starting with V7.4.0.
An added layer of security is provided by using Challenge Handshake Authentication
Protocol (CHAP) authentication.
Transmission Control Protocol (TCP) ports 3260 and 3265 are used for IP partnership
communications. Therefore, these ports must be open in firewalls between the systems.
Only a single Remote Copy (RC) data session per physical link can be established. It is
intended that only one connection (for sending/receiving Remote Copy data) is made for
each independent physical link between the systems.
The maximum throughput is restricted based on the use of 1 Gbps or 10 Gbps Ethernet
ports, and varies based on distance (for example, round-trip latency) and quality of
communication link (for example, packet loss):
– One 1 Gbps port might transfer up to 110 megabytes per second (MBps)
unidirectional, 190 MBps bidirectional
– Two 1 Gbps ports might transfer up to 220 MBps unidirectional, 325 MBps bidirectional
– One 10 Gbps port might transfer up to 240 MBps unidirectional, 350 MBps bidirectional
– Two 10 Gbps port might transfer up to 440 MBps unidirectional, 600 MBps bidirectional
For further information on IP replication requirements and limitations, and supported
configurations, please see IBM Knowledge Center for IBM Storwize V5000 at the following
link:
https://ibm.biz/BdjKnQ
Note: A physical link is the physical IP link between the two sites, A (local) and B
(remote). Multiple IP addresses on local system A could be connected (by Ethernet
switches) to this physical link. Similarly, multiple IP addresses on remote system B
could be connected (by Ethernet switches) to the same physical link. At any point in
time, only a single IP address on cluster A can form an RC data session with an IP
address on cluster B.
Note: The Bandwidth setting definition when the IP partnerships are created changed.
Previously, the bandwidth setting defaulted to 50 MB, and was the maximum transfer
rate from the primary site to the secondary site for initial sync/resyncs of volumes.
The Link Bandwidth setting is now configured by using megabits (Mb) not MB. You set
the Link Bandwidth setting to a value that the communication link can sustain, or to
what is allocated for replication. The Background Copy Rate setting is now a
percentage of the Link Bandwidth. The Background Copy Rate setting determines the
available bandwidth for the initial sync and resyncs or for GM with Change Volumes.
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