# Building and installing SCST

## Prerequisites

If the following packages have not yet been installed, install these now:

    bzip2
    gcc
    kernel-devel or kernel-default-devel
    kernel-modules-extra (only on Fedora)
    libelf-dev, libelf-devel or elfutils-libelf-devel
    libperl-dev or perl-devel
    make
    perl
    perl-Data-Dumper
    perl-ExtUtils-MakeMaker (not needed on Debian systems)
    rpm-build (only on RPM-based systems)
    tar

## Building SCST

The next step is to build and install SCST. How to do that depends on whether
or not your Linux distribution supports a package manager:

    make release
    if rpm -q glibc >/dev/null 2>&1; then
        rm -rf {,scstadmin/}rpmbuilddir
        make rpm
        sudo rpm -U $PWD/{,scstadmin/}rpmbuilddir/RPMS/*/*.rpm
    elif dpkg-query -s libc-bin >/dev/null 2>&1; then
        sudo apt install build-essential debhelper devscripts gcc make lintian quilt
        sudo apt install linux-headers-$(uname -r) || sudo apt install pve-headers-$(uname -r)
        make dpkg
        sudo dpkg -i $PWD/dpkg/{scst,iscsi-scst,scstadmin}_*.deb
    else
        make 2release
        BUILD_2X_MODULE=y CONFIG_SCSI_QLA_FC=y CONFIG_SCSI_QLA2XXX_TARGET=y make all
        sudo BUILD_2X_MODULE=y CONFIG_SCSI_QLA_FC=y CONFIG_SCSI_QLA2XXX_TARGET=y make -C "$PWD" install
    fi

Since the above step installs several kernel modules into directory
/lib/modules/$(uname -r), that step has to be repeated every time a new kernel
or a kernel update has been installed. If you want to avoid this, install the
scst-dkms package instead of the scst package. That will cause SCST to be
rebuilt and installed every time a kernel version is booted for which the SCST
kernel modules had not yet been built.

## Configuring SCST

The easiest way to configure SCST is to create a configuration file
/etc/scst.conf and by using scstadmin to load that configuration file. The
/etc/init.d/scst script uses scstadmin to load the /etc/scst.conf file. The
following information is present in /etc/scst.conf:

* Which local storage has to be exported by SCST, e.g. a file, block device or
  SCSI device.
* Through which storage adapter ports SCST allows access to the local
  storage.
* Which initiator systems are allowed to log in.

For more information about scst.conf, see also
scstadmin/scstadmin.sysfs/man5/scst.conf.5.

Loading the SCST kernel modules and applying the /etc/scst.conf configuration
file is possible as follows:

    /etc/init.d/scst restart

After SCST has been loaded, configuration changes can be applied without
unloading and reloading the SCST kernel modules:

    scstadmin -config /etc/scst.conf

After the SCST configuration has been changed via scstadmin or by modifying the
SCST sysfs attributes, the new configuration can be saved e.g. as follows:

    scstadmin -write_config /etc/scst.conf.new

More information about the device handler and target driver sysfs attributes
can be found in the scst/README document. More detailed instructions about
iSCSI, QLogic FC, SRP and FCoE configuration can be found in the following
documents:

* iscsi-scst/README
* qla2x00t/doc/qla2x00t-howto.html
* srpt/README
* fcst/README