I did some iperf testing on the two Availability Zones (AZ) in the Sydney AWS region. I have 4 gluster servers a m1.medium and m3.large in ap-southeast-2a and a m1.medium and m3.large in ap-southeast-2b. So I did a cross AZ iperf test between like servers.
m1.medium 2a > m1.medium 2b [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 220 MBytes 184 Mbits/sec [ 7] 0.0-10.0 sec 188 MBytes 157 Mbits/sec [ 6] 0.0-10.0 sec 193 MBytes 161 Mbits/sec [ 8] 0.0-10.1 sec 262 MBytes 218 Mbits/sec [SUM] 0.0-10.1 sec 863 MBytes 719 Mbits/sec [ 4] 0.0-10.1 sec 219 MBytes 181 Mbits/sec [ 6] 0.0-10.2 sec 227 MBytes 187 Mbits/sec [ 7] 0.0-10.2 sec 197 MBytes 162 Mbits/sec [ 3] 0.0-10.2 sec 221 MBytes 182 Mbits/sec [SUM] 0.0-10.2 sec 864 MBytes 712 Mbits/sec m3.large 2a > m3.large 2b [ ID] Interval Transfer Bandwidth [ 7] 0.0-10.0 sec 222 MBytes 185 Mbits/sec [ 3] 0.0-10.0 sec 66.0 MBytes 55.1 Mbits/sec [ 6] 0.0-10.1 sec 96.6 MBytes 80.6 Mbits/sec [ 8] 0.0-10.1 sec 56.8 MBytes 47.3 Mbits/sec [SUM] 0.0-10.1 sec 441 MBytes 368 Mbits/sec [ 7] 0.0-10.1 sec 140 MBytes 116 Mbits/sec [ 3] 0.0-10.1 sec 162 MBytes 134 Mbits/sec [ 6] 0.0-10.2 sec 79.1 MBytes 65.3 Mbits/sec [ 5] 0.0-10.2 sec 57.4 MBytes 47.4 Mbits/sec [SUM] 0.0-10.2 sec 438 MBytes 362 Mbits/sec
Not that good, not gigabit speeds, but not terrible.
Now keeping the test inside the same AZ.
m1.medium 2b > m3.large 2b [ ID] Interval Transfer Bandwidth [ 7] 0.0-10.0 sec 105 MBytes 87.6 Mbits/sec [ 6] 0.0-10.0 sec 161 MBytes 135 Mbits/sec [ 5] 0.0-10.1 sec 93.9 MBytes 78.3 Mbits/sec [ 8] 0.0-10.1 sec 86.4 MBytes 71.9 Mbits/sec [SUM] 0.0-10.1 sec 446 MBytes 371 Mbits/sec [ 5] 0.0-10.2 sec 143 MBytes 118 Mbits/sec [ 4] 0.0-10.2 sec 93.5 MBytes 77.0 Mbits/sec [ 7] 0.0-10.2 sec 119 MBytes 98.2 Mbits/sec [ 6] 0.0-10.2 sec 89.0 MBytes 73.3 Mbits/sec [SUM] 0.0-10.2 sec 445 MBytes 366 Mbits/sec
Not much better.