Clariion Offers Remote Mirroring

The Clariion Advanced Storage Division ( of Data General Corp. ( is aiming to improve disaster tolerance with Remote Mirroring. Clariion’s Remote Mirroring is a set of hardware, software, and services designed to safeguard corporate information assets against severe outages, including natural disasters and equipment and power failures.

By using SCSI over fiber optic cables, companies -- in most cases -- can store their data at a remote site up to 30 km, or 18.6 miles, away, making it possible to have the array on a different power grid. The service is available on the FC5700 Fibre Channel RAID disk arrays as well as the FC5500 and C3500 Series.

"With this kind of facility, you could be back online in a matter of minutes, as opposed to using tapes and trucking them to a facility somewhere," says Peter Gibbs, director of marketing for Clariion.

Clariion's solution takes care of data recovery, but a disaster recovery service should include copying the image of the company's network and providing nodes for clients to continue operating. Additionally, 30 km may not be far enough away to protect data from a wide-ranging disaster, such as a hurricane.

"This shouldn't be considered the disaster recovery plan," says Anders Lofgren, analyst with Giga Information Group ( "Really what we're talking about is something that may be part of the overall plan, not a replacement of it."

Clariion’s solution is available for servers running Sun Solaris and Microsoft Windows NT operating systems, with support to follow for IBM-AIX and HP-UX. Clariion Remote Mirroring includes the necessary hardware and software, as well as consulting, design and implementation services to help customers get online with the service.

Instead of designing its own packaged software, Clariion employed already-installed, host-based mirroring packages, such as Sun Enterprise Volume Manager and Windows NT Disk Administrator, as well as third-party packages such as Veritas Volume Manager.

Clariion Remote Mirroring is available in two options. The standard package supports mirrored storage over distances of up to 30 km by creating a separate storage zone at a remote site with duplicate host and storage configurations at each site. A high-availability package supports the standard configuration plus dual links between sites.

In theory, customers could take their remote mirroring as far as they want, but the cost structure, for one, stands in the way. Large financial institutions, such as Visa International (, are known to have huge arrays spaced throughout the world to defend against terrorism, mishaps or acts of God. The cost is unrealistic for most companies.

Traffic to the remote mirror can be slow. Each transaction to a storage facility usually includes a read and a write as well as the acknowledgment, Clariion's Gibbs explains. It is possible to configure the primary server to accept both the read and write while the secondary server only accepts the write command. This alteration cuts down heavily on throughput.

Gibbs says Remote Mirroring and other initiatives are beginning to expand the concept of a Storage Area Network (SAN). Instead of servers running applications, the array takes on some of that responsibility so that large enterprises can put a SAN in between a large pool of centralized storage to add value to that operation.

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