Adaptec 412R User Guide - Page 106

DuraStor 412R/6320SS/7320SS Installation and User's Guide four (4) host connections. You can enable or disable this feature using Disk Array Administrator. For a detailed discussion of each operating mode, see the section that applies to your DuraStor storage subsystem: For the DuraStor 6320SS, see the next section. For the DuraStor 7320SS, see page A-14. Operating Modes - DuraStor 6320SS Stand-Alone Mode In stand-alone mode, the RAID controller operates autonomously. The controller has two SCSI host I/O connector ports. They are labeled in the diagrams as "CH 0" and "CH 3." In single-port mode, the "CH 3" connector becomes a drive channel providing one additional drive channel for expansion. Advantages: I Low cost entry-level RAID storage solution that is field upgradeable. I Allows the use of dual host ports to maximize bandwidth and host IOPs. (For example: this configuration is ideal for sequential access patterns, where disks can supply more than 160 MB/sec of data to a host.) I Host system has multiple paths to each array (with host driver). I All arrays appear on both host ports at the same LUN positions in Dual Port mode. (If both ports are connected to the same host, the host will see a given array twice unless it does special processing to detect duplicate paths to array. A host device driver may provide this functionality.) I Hosts can detect redundant paths to an array by matching array serial numbers from SCSI inquiry data. Disadvantages: I The controller is a single point of failure. I Third-party software is required for upstream path fail-over. A-4