SCST is designed to provide unified, consistent interface between SCSI
target drivers and Linux kernel and simplify target drivers development
as much as possible. Detail description of SCST's features and internals
could be found on its Internet page http://scst.sourceforge.net.
target drivers and Linux kernel and simplify target drivers development
as much as possible. Detail description of SCST's features and internals
could be found on its Internet page http://scst.sourceforge.net.
SCST supports the following I/O modes:
* Pass-through mode with one to many relationship, i.e. when multiple
initiators can connect to the exported pass-through devices, for
the following SCSI devices types: disks (type 0), tapes (type 1),
processors (type 3), CDROMs (type 5), MO disks (type 7), medium
changers (type 8) and RAID controllers (type 0xC).
initiators can connect to the exported pass-through devices, for
the following SCSI devices types: disks (type 0), tapes (type 1),
processors (type 3), CDROMs (type 5), MO disks (type 7), medium
changers (type 8) and RAID controllers (type 0xC).
* FILEIO mode, which allows to use files on file systems or block
devices as virtual remotely available SCSI disks or CDROMs with
benefits of the Linux page cache.
devices as virtual remotely available SCSI disks or CDROMs with
benefits of the Linux page cache.
* BLOCKIO mode, which performs direct block IO with a block device,
bypassing page-cache for all operations. This mode works ideally with
high-end storage HBAs and for applications that either do not need
caching between application and disk or need the large block
throughput.
bypassing page-cache for all operations. This mode works ideally with
high-end storage HBAs and for applications that either do not need
caching between application and disk or need the large block
throughput.
* User space mode using scst_user device handler, which allows to
implement in the user space high performance virtual SCSI
devices. Comparing with fully in-kernel dev handlers this mode has
very low overhead (few %%)
implement in the user space high performance virtual SCSI
devices. Comparing with fully in-kernel dev handlers this mode has
very low overhead (few %%)
* "Performance" device handlers, which provide in pseudo pass-through
mode a way for direct performance measurements without overhead of
actual data transferring from/to underlying SCSI device.
mode a way for direct performance measurements without overhead of
actual data transferring from/to underlying SCSI device.
In addition, SCST supports advanced per-initiator access and devices
visibility management, so different initiators could see different set
of devices with different access permissions. See below for details.
visibility management, so different initiators could see different set
of devices with different access permissions. See below for details.
Full list of SCST features and comparison with other Linux targets you
can find on http://scst.sourceforge.net/comparison.html.
can find on http://scst.sourceforge.net/comparison.html.
转载于:https://blog.51cto.com/swanlet/915389