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Long-Term Storage & Compliance: CAS Vs. Locked NAS: Page 4 of 7

Nexsan's Assureon line allows an organization to add RAID arrays for simple storage or nodes with compute and storage capabilities at any time. Assureon also includes data de-duplication and MAID technologies to reduce the amount of storage needed and power consumption. Assureon can act as a RAID cache in front of optical disk or WORM tape libraries and includes a Windows file system watcher that will automatically copy files from any Windows file store when they're closed or reach an age that implies they're complete; if the systems guesses wrong, you'll end up archiving several drafts.

Finally, Caringo sells its CAStor as software distributed on a USB thumb drive that turns from two to //TK// standard Intel-based PC servers into a CAS cluster. Unlike EMC Centera, CAStor uses HTTP rather than a proprietary API as its primary interface, with CIFS/NFS access available as an add-on.

CAStor has the basic set of CAS features most organizations are looking for, including local and wide area replication, data retention, and replication depth definable at the object level. Still, while idea of building a large CAS cluster from standard servers and disk has a certain appeal, we don't think most enterprises will be comfortable rolling their own CAS systems.

Keep It Simpler
For all its inherent sexiness, CAS is a complicated solution to the problem of preventing users and administrators from deleting or modifying files. Several vendors, including Network Appliance through its optional SnapLock for filers running OnTap and Sun's StorageTek division through its StorEdge Compliance Archiving software, have added software-managed WORM to their NAS appliances.
Organizations can use the same NAS architectures, even the same appliances, as their primary file stores and still have a WORM archive. One system for backup, replication and management saves money and complexity.

Locked NAS is also easy on your application developers. Rather than having to integrate a new XML-based API to store and retrieve images or other files, they can simply write to the locked NAS via CIFS or NFS. Data retention periods can be defined on a folder-by-folder, or even a file-by-file, basis by setting the "file last accessed" time attribute to the end of the retention period and then flagging the file as read only.