Data Goes the Distance with WANs

Disaster recovery and business continuity are becoming priority projects for IT departments. However, managers need to do their homework before diving into the busy WAN replication market.

With disaster recovery and business continuity becoming priority projects for IT managers, a horde of solutions has emerged to help move data over WAN links and out of harms way.

WAN replication comes in many forms, so its extremely important for IT managers to do their homework before diving into the market. Replication technologies are built into storage arrays, appliances and software, giving IT managers many ways to move data—and many ways to make a mistake if they choose the wrong solution for their organization.

Before sending out RFPs (requests for proposals) to vendors for potential solutions, IT managers need to work with their organizations system administrators, developers and users to set implementation goals and determine the amount of resources that need to be dedicated.

SAN Gateway Solutions

Kashya Inc.s KBX5000 is an appliance that allows IT managers to extend their SANs (storage area networks) over WAN links . Because products such as the KBX5000 are designed primarily for Fibre Channel storage systems, they are most commonly seen at—and are more suitable for—large companies with bigger budgets that have already invested in SANs.

/zimages/6/28571.gifKashya has introduced a follow-up product to the KBX5000. Click here to read more.

Like other SAN gateway solutions, the KBX5000 hooks into Fibre Channel SANs, translates storage traffic into IP traffic and efficiently ships the packets over the WAN, where a receiving KBX5000 unit can feed the data to the remote SAN. And with McData Corp.s January acquisition of Computer Network Technology Corp.—the most established player in the SAN extension market—it seems clear that SAN switch vendors will be pushing IT managers to use replication products in conjunction with SAN switches to move their data.

Array-Based Systems

Another option for it managers who want a storage-centric replication system is to use the replication technologies built into their arrays.

EMC Corp.s Symmetrix Remote Data Facility is the most widely known array-based replication solution and is common in mission-critical environments. During the last few years, even smaller arrays, such as Compellents Storage Center, have added replication capabilities, making the technology accessible to more companies.

With its iSCSI-based PeerStorage array, EqualLogic Inc. takes this a step further—bundling replication-over-WAN capabilities for free. This is something we hope to see more of in the midrange storage market, as it will make important WAN replication capabilities available even to organizations that might not otherwise be able to afford it.

/zimages/6/28571.gifClick here to read a review of the PeerStorage Array 100E.

Software-Based Data Replication

Companies that have not implemented extensive SANs and still have a large amount of DAS (direct-attached storage) have several options.

Relatively inexpensive and easy to implement, software-based data replication systems are available from vendors including Symantec Corp., XOsoft Inc. and NSI Software Inc. Instead of focusing on moving and translating block-level storage across the WAN, these solutions work at the host level. Since they run on servers and are not tied to the storage hardware, they can be run in virtually any environment.

Performance is not a strength of these software-based solutions, but there are ways to squeeze more juice out of them.

Network Executive Software Inc.s HyperIP appliance, for example, can greatly increase the data transfer rates of software-based replication solutions. WAN acceleration systems such as the HyperIP and Riverbed Technology Inc.s Steelhead appliance minimize the inefficiencies of TCP/IP, allowing replication solutions to push data across the wire faster.

Senior Analyst Henry Baltazar can be reached at

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