What is "scst"

SCST is a GPL licensed SCSI target software stack. The design goals of this software stack are high performance, high reliability, strict conformance to existing SCSI standards, being easy to extend and easy to use. SCST does not only support multiple SCSI protocols ( iSCSI, FC, SRP, ...) but also supports multiple local storage interfaces (SCSI pass-through, block I/O and file I/O) and also storage drivers implemented in user-space via the scst_user driver.

In order to reach maximum performance SCST has been implemented as a set of kernel drivers. SCST is often combined with RAID, Deduplication and/or High-availability cluster software to augment its functionality. The SCST software stack is the basis software of many SAN systems. Several world records have been set with SAN systems based on SCST.

SCST competes with LIO Target for the same purpose of providing a generic SCSI target module inside the Linux kernel. For the narrower purpose providing a Linux iSCSI target, the older IET and STGT modules also enjoy industry support.

SCST is now primarily developed by SanDisk personnel, after Fusion-io acquired in 2013 the start-up ID7 which initially developed SCST and after SanDisk acquired Fusion-io in 2014.