MongoDB and FlashArray utilize asynchronous replication however, given the same network conditions hardware based (ActiveDR) replication can be more efficient. Based on testing in the Everpure laboratory, the replication lag (RPO) delivered by FlashArray during heavy write operations (50% writes) was up to 33% lower than MongoDB replication lag under the same workload. For the testing purposes YCSB (Yahoo! Cloud Serving Benchmark) with workload A (50% reads,50% writes) were utilized. This type of workload simulates applications such as live tracking systems. The database was built on a three node replica set. The MongoDB replication lag was collected based on the output of rs.printSlaveReplicationInfo() collected every 15 seconds. For flash array purepod replica-link list --lag --historical <time> with a 30 seconds reporting frequency. The chart shown in Figure 2 illustrates the maximum replication lag reported by FlashArray and MongodB. Lower replication lag means less potential data loss (recovery point objective) in case of the catastrophic data center failure.
Figure 2.