doc/iscsi: Add description about iSCSI login redirection

Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: Idac2940bac28b3513bb38c4fd6768fdb38f7a715
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/3494
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
This commit is contained in:
Shuhei Matsumoto 2020-07-23 12:29:24 +09:00 committed by Tomasz Zawadzki
parent d40a1b7eff
commit 49904470ba

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@ -325,3 +325,37 @@ At the iSCSI level, we provide the following support for Hotplug:
return back; after all the commands return back, the LUN will be deleted. return back; after all the commands return back, the LUN will be deleted.
@sa spdk_nvme_probe @sa spdk_nvme_probe
# iSCSI Login Redirection {#iscsi_login_redirection}
The SPDK iSCSI target application supports iSCSI login redirection feature.
A portal refers to an IP address and TCP port number pair, and a portal group
contains a set of portals. Users for the SPDK iSCSI target application configure
portals through portal groups.
To support login redirection feature, we utilize two types of portal groups,
public portal group and private portal group.
The SPDK iSCSI target application usually has a discovery portal. The discovery
portal is connected by an initiator to get a list of targets, as well as the list
of portals on which these target may be accessed, by a discovery session.
Public portal groups have their portals returned by a discovery session. Private
portal groups do not have their portals returned by a discovery session. A public
portal group may optionally have a redirect portal for non-discovery logins for
each associated target. This redirect portal must be from a private portal group.
Initiators configure portals in public portal groups as target portals. When an
initator logs in to a target through a portal in an associated public portal group,
the target sends a temporary redirection response with a redirect portal. Then the
initiator logs in to the target again through the redirect portal.
Users set a portal group to public or private at creation using the
`iscsi_create_portal_group` RPC, associate portal groups with a target using the
`iscsi_create_target_node` RPC or the `iscsi_target_node_add_pg_ig_maps` RPC, and
specify a up-to-date redirect portal in a public portal group for a target using
`iscsi_target_node_set_redirect` RPC.
Typically users will use the login redirection feature in scale out iSCSI target
system, which runs multiple SPDK iSCSI target applications.