Continuous Access Eva With Vcs 4.X; Network Requirements For Long-Distance Ip Gateways With Vcs 4.X - HP StorageWorks 4000/6000/8000 - Enterprise Virtual Arrays Reference Manual

Continuous Access EVA with VCS 4.x

This section describes the VCS 4.x data replication specifications and the supported minimum and
maximum transmission rates for qualified switch and gateway pairs.
Table 161 lists the network requirements for long-distance IP gateways that work with EVA VCS 4.x.
Table 161 Network requirements for long-distance IP gateways with VCS 4.x
Specification
1
IP bandwidth
Maximum number of DR groups
MTU of the IP network
Maximum latency
Average packet-loss ratio
3
Latency jitter
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 162
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.
332 SAN extension
Must be dedicated to the Continuous Access storage replication
function.
The minimum IP bandwidth required for Continuous Access EVA 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.
See Table 131
See Table
bandwidth and resulting maximum number of DR groups based on the
average packet-loss ratio and one-way inter-site latencies.
1,500 bytes
1
100 ms one-way or 200 ms round-trip
2 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
Must not exceed 10 ms over 24 hours
and Table 163 are supported in both low-loss and high-loss networks.
Description
for the maximum number of DR groups.
162, Table 163, and Table 164 for minimum supported