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samba-mirror/ctdb/doc
Martin Schwenke 4569c65288 ctdb-scripts: Add configuration variable CTDB_KILLTCP_USE_SS_KILL
This allows CTDB to be configured to use "ss -K" to reset TCP
connections on "releaseip".  This is only supported when the kernel is
configured with CONFIG_INET_DIAG_DESTROY enabled.

From the documentation:

   ss -K has been supported in ss since iproute 4.5 in March 2016 and
   in the Linux kernel since 4.4 in December 2015.  However, the
   required kernel configuration item CONFIG_INET_DIAG_DESTROY is
   disabled by default.  Although enabled in Debian kernels since
   ~2017 and in Ubuntu since at least 18.04,, this has only recently
   been enabled in distributions such as RHEL.  There seems to be no
   way, including running ss -K, to determine if this is supported, so
   use of this feature needs to be configurable.  When available, it
   should be the fastest, most reliable way of killing connections.

For RHEL and derivatives, this was enabled as follows:

* RHEL 8 via https://bugzilla.redhat.com/show_bug.cgi?id=2230213,
  arriving in version kernel-4.18.0-513.5.1.el8_9

* RHEL 9 via https://issues.redhat.com/browse/RHEL-212, arriving in
  kernel-5.14.0-360.el9

Enabling this option results in a small behaviour change because ss -K
always does a 2-way kill (i.e. it also sends a RST to the client).
Only a 1-way kill is done for SMB connections when ctdb_killtcp is
used - the reasons for this are shrouded in history and the 2-way kill
seems to work fine.

For the summary that is logged, when CTDB_KILLTCP_USE_SS_KILL is "yes"
or "try", always log the method used, even the fallback to
ctdb_killtcp.  However, when set to "no", maintain the existing
output.

The decision to use -K rather than --kill is because short options are
trivial to implement in test stubs.

Signed-off-by: Martin Schwenke <mschwenke@ddn.com>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jerry Heyman <jheyman@ddn.com>

Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Thu Nov  7 00:12:34 UTC 2024 on atb-devel-224
2024-11-07 00:12:34 +00:00
..
examples ctdb-scripts: Add support for backing up persistent TDBs 2024-08-29 22:48:33 +00:00
cluster_mutex_helper.txt ctdb-config: [cluster] recovery lock -> [cluster] cluster lock 2022-01-17 10:21:33 +00:00
ctdb_diagnostics.1.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ctdb_mutex_ceph_rados_helper.7.xml ctdb/docs: Include ceph rados namespace support in man page 2024-06-14 07:42:25 +00:00
ctdb-etcd.7.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ctdb-script.options.5.xml ctdb-scripts: Add configuration variable CTDB_KILLTCP_USE_SS_KILL 2024-11-07 00:12:34 +00:00
ctdb-statistics.7.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ctdb-tunables.7.xml docs-xml: Fix documentation 2023-10-25 22:23:37 +00:00
ctdb.1.xml ctdb-scripts: Move database handling to its own event script 2024-08-29 22:48:33 +00:00
ctdb.7.xml ctdb-doc: document nodes list configuration parameter 2024-08-06 01:50:12 +00:00
ctdb.conf.5.xml ctdb-tcp: Only attempt to automatically bind to local IPs 2024-10-07 15:58:38 +00:00
ctdb.sysconfig.5.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ctdbd.1.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ltdbtool.1.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
onnode.1.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
ping_pong.1.xml ctdb-doc: Update CTDB manual pages to UTF-8 2023-10-03 03:53:35 +00:00
readonlyrecords.txt ctdb:doc: Fix code spelling 2023-04-04 07:31:36 +00:00