.SAN design reference guide Vol. 1-5 785350-001

pairs. Table 148 (page 299) lists the network requirements for long-distance gateways that work

with EVA XCS 6.x.

Table 148 Network requirements for long-distance IP gateways with XCS 6.

DescriptionSpecification

IP bandwidth

• Must be dedicated to the HP P6000 Continuous Access storage replication

function.

• The minimum IP bandwidth required for HP P6000 Continuous Access with

FCIP is 2 Mb/s per path, or 4 Mb/s for two paths when using one IP link.

• There is no support for dynamic pacing of the gateway.

For the maximum number of DR groups, see Table 114 (page 228).

Maximum number of DR groups

for minimum supported bandwidth and resulting maximum number of DR

groups based on the average packet-loss ratio and one-way inter-site latencies,

see Table 149 (page 300) and Table 150 (page 301).

1,500 bytesMTU of the IP network

100 ms IP network delay one-way or 200 ms round-tripMaximum latency

Low-loss network: 0.0012% average over 24 hours

Average packet-loss ratio

High-loss network: 0.2% average over 24 hours; must not exceed 0.5% for

more than 5 minutes in a two-hour window

Must not exceed 10 ms over 24 hoursLatency jitter

Pre-existing restriction

A high packet-loss ratio indicates the need to retransmit data across the inter-site link. Each retransmission delays

transmissions queued behind the current packet, thus increasing the time to complete pending transactions. Unless noted

otherwise, gateways listed in Table 149 (page 300) and Table 150 (page 301) are supported in both low-loss and high-loss

networks.

Latency jitter is the difference between the minimum and maximum values, and indicates how stable or predictable the

network delay. The greater the jitter, the greater the variance in the delay, which lowers the performance predictability.

NOTE: Applications typically require more than the minimum bandwidth to meet throughput

requirements. To increase the maximum number of DR groups, you must increase the minimum

available IP bandwidth. For example, if the maximum number of DR groups required is 10, increase

the minimum available bandwidth to 10 Mb/s; for 15 DR groups, increase to 15 Mb/s; and for

128 DR groups, increase the minimum available bandwidth to 128 Mb/s.

Table 149 (page 300) describes the network bandwidth requirements and IP gateway support for

XCS 6.x with B-series switches.

HP storage replication products 299