.. _ceph-iscsi:

==================
Ceph iSCSI Gateway
==================

The iSCSI Gateway presents
a Highly Available (HA) iSCSI target that exports RADOS Block Device (RBD) images
as SCSI disks. The iSCSI protocol allows clients (initiators) to send SCSI commands
to storage devices (targets) over a TCP/IP network, enabling clients without
native Ceph client support to access Ceph block storage.  These include
Microsoft Windows and even BIOS.

Each iSCSI gateway exploits the Linux IO target kernel subsystem (LIO) to provide
iSCSI protocol support. LIO utilizes userspace passthrough (TCMU) to interact
with Ceph's librbd library and expose RBD images to iSCSI clients. With Ceph’s
iSCSI gateway you can provision a fully integrated block-storage
infrastructure with all the features and benefits of a conventional Storage Area
Network (SAN).

.. ditaa::
                  Cluster Network (optional)
                 +-------------------------------------------+
                 |             |               |             |
             +-------+     +-------+       +-------+     +-------+
             |       |     |       |       |       |     |       |
             | OSD 1 |     | OSD 2 |       | OSD 3 |     | OSD N |
             |    {s}|     |    {s}|       |    {s}|     |    {s}|
             +-------+     +-------+       +-------+     +-------+
                 |             |               |             |
      +--------->|             |  +---------+  |             |<---------+
      :          |             |  |   RBD   |  |             |          :
      |          +----------------|  Image  |----------------+          |
      |           Public Network  |    {d}  |                           |
      |                           +---------+                           |
      |                                                                 |
      |                      +-------------------+                      |
      |   +--------------+   | iSCSI Initiators  |   +--------------+   |
      |   | iSCSI GW     |   |   +-----------+   |   | iSCSI GW     |   |
      +-->|  RBD Module  |<--+   | Various   |   +-->|  RBD Module  |<--+
          |              |   |   | Operating |   |   |              |
          +--------------+   |   | Systems   |   |   +--------------+
                             |   +-----------+   |
                             +-------------------+


.. toctree::
  :maxdepth: 1

  Requirements <iscsi-requirements>
  Configuring the iSCSI Target <iscsi-targets>
  Configuring the iSCSI Initiators <iscsi-initiators>
  Monitoring the iSCSI Gateways <iscsi-monitoring>