HP StorageWorks 4000/6000/8000 - Enterprise Virtual Arrays, Reference Manual

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gateway pairs. Table 154 lists the network requirements for long-distance gateways that work with
EVA4400 and EVA4400 (embedded switch) XCS 09 x .
Table 154 Network requirements for long-distance IP gateways with XCS 09x
Description Specification
• Must be dedicated to the Continuous Access storage replication function.
• The minimum IP bandwidth required for Continuous Access
EVA4400/6400/8400 and EVA4400 (embedded switch) 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.
IP bandwidth
1
See Table 131 for the maximum number of DR groups.
See Table 155 and Table 156 for minimum supported bandwidth and resulting
maximum number of DR groups based on the average packet-loss ratio and
one-way inter-site latencies.
Maximum number of DR
groups
1,500 bytes MTU of the IP network
100 ms IP network delay one-way or 200 ms round-trip
Maximum latency
1
Low-loss network: 0.0012% average over 24 hours
High-loss network: 0.2% average over 24 hours; must not exceed 0.5% for more
than 5 minutes in a two-hour window
Average packet-loss ratio
2
Must not exceed 10 ms over 24 hours
Latency jitter
3
1
Pre-existing restriction
2
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 155 and Table 156 are supported in both low-loss and high-loss networks.
3
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 it to 15 Mb/s; and for 128 DR groups,
increase it to 128 Mb/s.
Table 155 describes the network bandwidth requirements and IP gateway support for XCS 09 x with B-series
switches.
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