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NetEx Reaches Out to Replicators

Network Executive Software Inc. (NetEx) has relaunched its WAN optimization appliance with a focus on remote replication. With HyperIP DRO (Data Replication Optimizer), the vendor claims to boost throughput from three to ten times for specific replication products (see NetEx Releases HyperIP).

Now, ask any replication vendor whether their product has issues over distance, and you're apt to get a resounding "No!" But at least one industry observer, who requested anonymity, says it just ain't so.

"If you ask the replication vendors whether they have distance limitations, they'll say no, and they'll be correct, technically. Replication applications do nothing about network performance. Most storage guys are stupid when it comes to network timing, distance, and latency," the source says.

Like any application, asynchronous replication gathers the 'L' word -- latency -- over distance, to the tune of about 1 millisecond per 100 miles. What's more, jitter, and the numerous retransmissions that result from other disruptions on IP networks, can accumulate, slowing backups or, worse, making them unreliable.

Sources say the problem is heartrendingly evident in iSCSI networks, where smaller firms have opted for IP specifically because they can't afford the high cost of a Fibre Channel SAN for disaster recovery (see iSCSI Tackles DR). Ironically, their choice can backfire unless some help is provided to deal with the IP issues.

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