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A final concern is the protocols used to access the RAIN nodes. One way RAIN vendors circumvent the API problem is by presenting a mountable file system to the OS and allowing apps to use the more common NFS and CIFS protocols to store and retrieve data. Most RAIN vendors, including Archivas, Bycast, HP and Permabit, support this configuration, and even EMC is jumping on the bandwagon.
|Pros and cons of RAIN products|
|Click here for a comprehensive list of the pros and cons of RAIN products (PDF).|
NetApp's NAS products use file systems, but they support CAS in a slightly different manner. By using SnapLock (an optional WORM feature) with the Data Ontap OS that comes standard with all NetApp filers, and its new Advanced Single Instance Storage (ASIS) feature, users can lock down data and optimize storage capacity on filers. The main drawback of file-system architectures is that they require either a separate appliance or third-party software such as Open Text or FileNet to classify each file, create and store meta data, and manage the file's data-retention periods and user access permissions.
IBM prepackages its TotalStorage DR550 with TSM for Data Retention software to enable apps to classify and manage data. (Shops already using TSM can host the Data Retention component on an existing TSM server.) For small- to medium-sized firms, IBM offers DR550 Express, which also ships with the TSM software, but supports only internal disk drives with an option for tape vs. the DR550 that supports external disk and tape and is available in clustered configurations. TSM is required to manage data placement, retention and security policies; all host apps will need to support TSM's APIs to store and retrieve data.
This was first published in June 2006