Message-Id: <1404251250-22992-49-git-send-email-tst@schoebel-theuer.de>
Date:	Tue,  1 Jul 2014 23:47:28 +0200
From:	Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 48/50] mars: add new file drivers/block/mars/Kconfig

Signed-off-by: Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
---
 drivers/block/mars/Kconfig | 371 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 371 insertions(+)
 create mode 100644 drivers/block/mars/Kconfig

diff --git a/drivers/block/mars/Kconfig b/drivers/block/mars/Kconfig
new file mode 100644
index 0000000..89765f2
--- /dev/null
+++ b/drivers/block/mars/Kconfig
@@ -0,0 +1,371 @@
+#
+# MARS configuration
+#
+
+config MARS
+	tristate "storage system MARS (EXPERIMENTAL)"
+	depends on BLOCK && PROC_SYSCTL && HIGH_RES_TIMERS && !DEBUG_SLAB && !DEBUG_SG
+	default n
+	---help---
+	  MARS is a long-distance replication of generic block devices.
+	  It works asynchronously and tolerates network bottlenecks.
+	  Please read the full documentation at
+	    https://github.com/schoebel/mars/blob/master/docu/mars-manual.pdf?raw=true
+	  Always compile MARS as a module!
+
+config MARS_CHECKS
+	bool "enable simple runtime checks in MARS"
+	depends on MARS
+	default y
+	---help---
+	  These checks should be rather lightweight. Use them
+	  for beta testing and for production systems where
+	  safety is more important than performance.
+	  In case of bugs in the reference counting, an automatic	repair
+	  is attempted, which lowers the risk of memory corruptions.
+	  Disable only if you need the absolutely last grain of
+	  performance.
+	  If unsure, say Y here.
+
+config MARS_DEBUG
+	bool "enable full runtime checks and some tracing in MARS"
+	depends on MARS
+	default n
+	---help---
+	  Some of these checks and some additional error tracing may
+	  consume noticable amounts of memory. However, this is extremely
+	  valuable for finding bugs, even in production systems.
+
+	  OFF for production systems. ON for testing!
+
+	  If you encounter bugs in production systems, you
+	  may / should use this also in production if you carefully
+	  monitor your systems.
+
+config MARS_DEBUG_MEM
+	bool "debug memory operations"
+	depends on MARS_DEBUG
+	default n
+	---help---
+	  This adds considerable space and time overhead, but catches
+	  many errors (including some that are not caught by kmemleak).
+
+	  OFF for production systems. ON for testing!
+	  Use only for development and thorough testing!
+
+config MARS_DEBUG_MEM_STRONG
+	bool "intensified debugging of memory operations"
+	depends on MARS_DEBUG_MEM
+	default y
+	---help---
+	  Trace all block allocations, find more errors.
+	  Adds some overhead.
+
+	  Use for debugging of new bricks or for intensified
+	  regression testing.
+
+config MARS_DEBUG_ORDER0
+	bool "also debug order0 operations"
+	depends on MARS_DEBUG_MEM
+	default n
+	---help---
+	  Turn even order 0 allocations into order 1 ones and provoke
+	  heavy memory fragmentation problems from the buddy allocator,
+	  but catch some additional memory problems.
+	  Use only if you know what you are doing!
+	  Normally OFF.
+
+config MARS_DEFAULT_PORT
+	int "port number where MARS is listening"
+	depends on MARS
+	default 7777
+	---help---
+	  Best practice is to uniformly use the same port number
+	  in a cluster. Therefore, this is a compiletime constant.
+	  You may override this at insmod time via the mars_port= parameter.
+
+config MARS_SEPARATE_PORTS
+	bool "use separate port numbers for traffic shaping"
+	depends on MARS
+	default y
+	---help---
+	  When enabled, the following port assignments will be used:
+
+	  CONFIG_MARS_DEFAULT_PORT     : updates of symlinks
+	  CONFIG_MARS_DEFAULT_PORT + 1 : replication of logfiles
+	  CONFIG_MARS_DEFAULT_PORT + 2 : (initial) sync traffic
+
+	  As a consequence, external traffic shaping may be used to
+	  individually control the network speed for different types
+	  of traffic.
+
+	  Please don't hinder the symlink updates in any way -- they are
+	  most vital, and they produce no mass traffic at all
+	  (it's only some kind of  meta-information traffic).
+
+	  Say Y if you have a big datacenter.
+	  Say N if you cannot afford a bigger hole in your firefall.
+	  If unsure, say Y.
+
+
+config MARS_LOGDIR
+	string "absolute path to the logging directory"
+	depends on MARS
+	default "/mars"
+	---help---
+	  Path to the directory where all MARS messages will reside.
+	  Usually this is equal to the global /mars directory.
+
+	  Logfiles and status files obey the following naming conventions:
+		0.debug.log
+		1.info.log
+		2.warn.log
+		3.error.log
+		4.fatal.log
+		5.total.log
+	  Logfiles must already exist in order to be appended.
+	  Logiles can be rotated by renaming them and creating
+	  a new empty file in place of the old one.
+
+	  Status files follow the same rules, but .log is replaced
+	  by .status, and they are created automatically. Their content
+	  is however limited to a few seconds or minutes.
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_ROLLOVER_INTERVAL
+	int "rollover time of logging status files (in seconds)"
+	depends on MARS
+	default 3
+	---help---
+	  This may influence the system load; dont use too low numbers.
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_SCAN_INTERVAL
+	int "re-scanning of symlinks in /mars/ (in seconds)"
+	depends on MARS
+	default 5
+	---help---
+	  This may influence the system load; dont use too low numbers.
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_PROPAGATE_INTERVAL
+	int "network propagation delay of changes in /mars/ (in seconds)"
+	depends on MARS
+	default 5
+	---help---
+	  This may influence the system load; dont use too low numbers.
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_SYNC_FLIP_INTERVAL
+	int "interrpt sync by logfile update after (seconds)"
+	depends on MARS
+	default 60
+	---help---
+	  0 = OFF. Normally ON.
+	  When disabled, application of logfiles may wait for
+	  a very time, until full sync has finished. As a
+	  consequence, your /mars/ filesystem may run out
+	  of space. When enabled, the applied logfiles can
+	  be deleted, freeing space on /mars/. Therefore,
+	  will usually want this. However, you may increase
+	  the time interval to increase throughput in favour
+	  of latency.
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_NETIO_TIMEOUT
+	int "timeout for remote IO operations (in seconds)"
+	depends on MARS
+	default 30
+	---help---
+	  In case of network hangs, don't wait forever, but rather
+	  abort with -ENOTCONN
+	  when == 0, wait forever (may lead to hanging operations
+	  similar to NFS hard mounts)
+
+	  Leave this at the default unless you know what you are doing.
+
+config MARS_FAST_FULLSYNC
+	bool "decrease network traffic at initial sync"
+	depends on MARS
+	default y
+	---help---
+	  Normally ON.
+	  When on, both sides will read the data, compute a md5
+	  checksum, and compare them. Only in case the checksum
+	  mismatches, the data will be actually transferred over
+	  the network. This may increase the IO traffic in favour
+	  of network traffic. Usually it does no harm to re-read
+	  the same data twice (only in case of mismatches) over bio
+	  because RAID controllers will usually cache their data
+	  for some time. In case of buffered aio reads from filesystems,
+	  the data is cached by the kernel anyway.
+
+config MARS_MIN_SPACE_4
+	int "absolutely necessary free space in /mars/ (hard limit in GB)"
+	depends on MARS
+	default 2
+	---help---
+	  HARDEST EMERGENCY LIMIT
+
+	  When free space in /mars/ drops under this limit,
+	  transaction logging to /mars/ will stop at all,
+	  even at all primary resources. All IO will directly go to the
+	  underlying raw devices. The transaction logfile sequence numbers
+	  will be disrupted, deliberately leaving holes in the sequence.
+
+	  This is a last-resort desperate action of the kernel.
+
+	  As a consequence, all secodaries will have no chance to
+	  replay at that gap, even if they got the logfiles.
+	  The secondaries will stop at the gap, left in an outdated,
+	  but logically consistent state.
+
+	  After the problem has been fixed, the secondaries must
+	  start a full-sync in order to continue replication at the
+	  recent state.
+
+	  This is the hardest measure the kernel can take in order
+	  to TRY to continue undisrupted operation at the primary side.
+
+	  In general, you should avoid such situations at the admin level.
+
+	  Please implement your own monitoring at the admin level,
+	  which warns you and/or takes appropriate countermeasures
+	  much earlier.
+
+	  Never rely on this emergency feature!
+
+config MARS_MIN_SPACE_3
+	int "free space in /mars/ for primary logfiles (additional limit in GB)"
+	depends on MARS
+	default 2
+	---help---
+	  MEDIUM EMERGENCY LIMIT
+
+	  When free space in /mars/ drops under
+	  MARS_MIN_SPACE_4 + MARS_MIN_SPACE_3,
+	  elder transaction logfiles will be deleted at primary resources.
+
+	  As a consequence, the secondaries may no longer be able to
+	  get a consecute series of copies of logfiles.
+	  As a result, they may get stuck somewhere inbetween at an
+	  outdated, but logically consistent state.
+
+	  This is a desperate action of the kernel.
+
+	  After the problem has been fixed, some secondaries may need to
+	  start a full-sync in order to continue replication at the
+	  recent state.
+
+	  In general, you should avoid such situations at the admin level.
+
+	  Please implement your own monitoring at the admin level,
+	  which warns you and/or takes appropriate countermeasures
+	  much earlier.
+
+	  Never rely on this emergency feature!
+
+config MARS_MIN_SPACE_2
+	int "free space in /mars/ for secondary logfiles (additional limit in GB)"
+	depends on MARS
+	default 2
+	---help---
+	  MEDIUM EMERGENCY LIMIT
+
+	  When free space in /mars/ drops under
+	  MARS_MIN_SPACE_4 + MARS_MIN_SPACE_3 + MARS_MIN_SPACE_2,
+	  elder transaction logfiles will be deleted at secondary resources.
+
+	  As a consequence, some local secondary resources
+	  may get stuck somewhere inbetween at an
+	  outdated, but logically consistent state.
+
+	  This is a desperate action of the kernel.
+
+	  After the problem has been fixed and the free space becomes
+	  larger than MARS_MIN_SPACE_4 + MARS_MIN_SPACE_3 + MARS_MIN_SPACE_2
+	  + MARS_MIN_SPACE_2, the secondary tries to fetch the missing
+	  logfiles from the primary again.
+
+	  However, if the necessary logfiles have been deleted at the
+	  primary side in the meantime, this may fail.
+
+	  In general, you should avoid such situations at the admin level.
+
+	  Please implement your own monitoring at the admin level,
+	  which warns you and/or takes appropriate countermeasures
+	  much earlier.
+
+	  Never rely on this emergency feature!
+
+config MARS_MIN_SPACE_1
+	int "free space in /mars/ for replication (additional limit in GB)"
+	depends on MARS
+	default 2
+	---help---
+	  LOWEST EMERGENCY LIMIT
+
+	  When free space in /mars/ drops under MARS_MIN_SPACE_4
+	  + MARS_MIN_SPACE_3 + MARS_MIN_SPACE_2 + MARS_MIN_SPACE_1,
+	  fetching of transaction logfiles will stop at local secondary
+	  resources.
+
+	  As a consequence, some local secondary resources
+	  may get stuck somewhere inbetween at an
+	  outdated, but logically consistent state.
+
+	  This is a desperate action of the kernel.
+
+	  After the problem has been fixed and the free space becomes
+	  larger than MARS_MIN_SPACE_4 + MARS_MIN_SPACE_3 + MARS_MIN_SPACE_2
+	  + MARS_MIN_SPACE_2, the secondary will continue fetching its
+	  copy of logfiles from the primary side.
+
+	  In general, you should avoid such situations at the admin level.
+
+	  Please implement your own monitoring at the admin level,
+	  which warns you and/or takes appropriate countermeasures
+	  much earlier.
+
+	  Never rely on this emergency feature!
+
+config MARS_MIN_SPACE_0
+	int "total space needed in /mars/ for (additional limit in GB)"
+	depends on MARS
+	default 12
+	---help---
+	  Operational pre-requirement.
+
+	  In order to use MARS, the total space available in /mars/ must
+	  be  at least MARS_MIN_SPACE_4 + MARS_MIN_SPACE_3 + MARS_MIN_SPACE_2
+	  + MARS_MIN_SPACE_1 + MARS_MIN_SPACE_0.
+
+	  If you cannot afford that amount of storage space, please use
+	  DRBD in place of MARS.
+
+config MARS_LOGROT_AUTO
+	int "automatic logrotate when logfile exceeds size (in GB)"
+	depends on MARS
+	default 32
+	---help---
+	  You could switch this off by setting to 0. However, deletion
+	  of really huge logfiles can take several minutes, or even substantial
+	  fractions of hours (depending on the underlying filesystem).
+	  Thus it is highly recommended to limit the logfile size to some
+	  reasonable maximum size. Switch only off for experiments!
+
+## remove_this
+config MARS_PREFER_SIO
+	bool "prefer sio bricks instead of aio"
+	depends on MARS_DEBUG
+	default n
+	---help---
+	  Normally OFF for production systems.
+	  Only use as alternative for testing.
+
+## end_remove_this
-- 
2.0.0

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