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The '''Digital Storage System Interconnect''', or '''DSSI''', is a single-path, daisy-chained, multidrop bus developed by DEC in 1988 as a smaller and cheaper replacement for the [[CI|Computer Interconnect]]. DSSI is supported by MIPS-based DECsystems and Alpha Server.

=Features and Uses=

DSSI configurations use HSD intelligent controllers to connect disk drives to an OpenVMS Cluster. Alternatively, DSSI configurations use integrated storage elements (ISEs) connected directly to the DSSI bus. Each ISE contains either a disk and disk controller or a tape and tape controller.

DSSI provides a single, 8-bit parallel data path with both byte parity and packet checksum for error detection. The maximum bandwidth of a DSSI bus if 32 Mbps and the total length is about 25m. DSSI became a precurson ro the SCSI standard. A VAX cluster can have up to 4 OpenVMS Systems on a shared DSSI bus and up to 4 integrated storage element disks or tapes.

=Hardware Support=

The systems that support DSSI include:
* AlphaServer 8400, 8200
* AlphaServer 4100, 2100, 2000
* AlphaServer 1000
* AlphaServer 400
* DEC 7000/10000
* DEC 4000
* VAX 6000/7000/10000
* VAX 4000, MicroVAX 3100

=See also=
* [https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04622356 Guidelines for OpenVMS Cluster Configurations]
* [http://manx-docs.org/collections/mds-199909/cd1/cluster/410abmgd.pdf DSSI VMS Cluster Installation and Troubleshooting Guide]