I would use SnapMirror with multiplexing mode (2 interfaces). From the online data protection guide the example below is multi using e0a and e1a on each system and you specify the connection in the snapmirror.conf file on the target. Usually we direct attach side-by-side then use different subnets for each connection. SnapMirror handles the 2 networks and sends traffic over both concurrently. If you can sustain two gig links without impacting the source performance you could leave it open without a throttle.
name=multi(src_system-e0a,dst_system-e0a)(src_system-e1a,dst_system-e1a)
If you hav a fast system and enough resources, you could push 2x 1GB links and get near 200MB/sec with enough streams. However, 1.5Petabytes is a lot...unless my math is wrong, it would be 90+ days.
PB 1.5
TB 1536
GB 1,572,864
MB 1,610,612,736
MB/sec 200
Seconds 8,053,063.68
minutes 134,217.73
hours 2,236.96
days 93.20675556
