mars/Kconfig
2013-01-20 23:24:24 +01:00

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#
# MARS configuration
#
config MARS
tristate "storage system MARS (EXPERIMENTAL)"
default n
---help---
Experimental storage System. Only compile as a module!
config MARS_DEBUG
bool "enable runtime checks in MARS"
depends on MARS
default n
---help---
OFF for production systems. ON for testing!
config MARS_BIGMODULE
tristate "compile all MARS modules into a single kernel module"
depends on MARS
default m
select MARS_HAVE_BIGMODULE
---help---
Normally ON. Switch off only for EXPERIMENTS!
config MARS_MEM_RETRY
bool "make MARS memory allocation more robust"
depends on MARS
default y
---help---
Normally ON. Switch only off for systems having very low memory.
config MARS_LOGFILE
string "full path to the logfile"
depends on MARS
default "/mars/log.txt"
---help---
Path to the logfile where all MARS messages go to.
The logfile 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.
When none exists, messages are either reported to syslog when
CONFIG_MARS_USE_SYSLOG is set, or else MARS will be qiet.
config MARS_USE_SYSLOG
bool "use syslog for messages"
depends on MARS
default n
---help---
Normally OFF.
When switched on (and no logfile exists), the syslog
may get flooded by printk() messages, leading to performance
problems if remote syslog forwarding is enabled (and possibly
in other cases). Thus we recommend to prefer file logging.
When this option is off, the logfile will be used (if one exists).
config MARS_SCAN_INTERVAL
int "re-scanning of symlinks in /mars/ (in seconds)"
depends on MARS
default 5
---help---
May influence the system load; dont use too low nubmers.
config MARS_PROPAGATE_INTERVAL
int "network propagation delay of changes in /mars/ (in seconds)"
depends on MARS
default 5
---help---
May influence the system load; dont use too low nubmers.
config MARS_FAST_TRIGGER
bool "fast internal triggering"
depends on MARS
default y
---help---
Normally ON. Switch off in case of endless trigger loops
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)
config MARS_MEM_PREALLOC
bool "avoid memory fragmentation by preallocation"
depends on MARS
default y
---help---
Normally ON. Switch off only for EXPERIMENTS!
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_LOADAVG_LIMIT
bool "stall copy traffic when loadavg gets too high"
depends on MARS
default y
---help---
Normally ON.
config MARS_LINEAR_CACHE_SIZE
int "cache size for linear scans of logfiles (in MB)"
depends on MARS
default 64
---help---
Setting this to high numbers (or disabling by setting to 0)
may disturb the application performance, because MARS will
pollute the page cache with pages from the MARS logfiles.
Setting this to low numbers will prevent such a pollution,
at the cost of (sometimes) more IO operations.
EXCEPTION: when you run MARS on a standalone storage server
(e.g. exporting devices via iSCSI), you should use high numbers
here or even disable this feature. THEN (and ONLY THEN)
you want MARS to use all the memory for its own caching,
since there is no other application competing for main memory.
In unsure, take the default of 64.
#config MARS_HUNG
# bool "hangup on kernel stacktrace (EXPERIMENTAL!!!)"
# depends on MARS && MARS_BIGMODULE!=m
# default n
# ---help---
# Normally OFF. Switch on only for EXPERIMENTS!
config MARS_LOGROT
bool "allow logrotate during operation"
depends on MARS
default y
---help---
Normally ON. Switch off only for EXPERIMENTS!
config MARS_LOGROT_AUTO
int "automatic logrotate when logfile exceeds size (in GB)"
depends on MARS_LOGROT
default 32
---help---
You could switch this off by setting to 0. However, deletion
of really huge logfile 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!
config MARS_MIN_SPACE
bool "check for filesystem overflow in /mars"
depends on MARS
default y
---help---
Normally ON. Switch off only for EXPERIMENTS!
config MARS_MIN_SPACE_BASE
int "free space in /mars/ (hard limit in gigabytes)"
depends on MARS_MIN_SPACE
default 8
---help---
when this limit is exceeded, all write requests to /mars/
will stop. This affects not only write IO to /dev/mars/*,
but also logfile transfers etc.
In order to retain full operations, you _need_ to implement
your own monitoring which _must_ warn you long before this
hard limit catches you.
config MARS_MIN_SPACE_PERCENT
int "free space in /mars/ (hard limit in percent)"
depends on MARS_MIN_SPACE
default 0
---help---
this limit is in addition to CONFIG_MARS_MIN_SPACE_BASE.
config MARS_LOGDELETE_AUTO
int "automatic log-delete when space in /mars/ gets short (in GB)"
depends on MARS_MIN_SPACE
default 8
---help---
This limit is in addition to CONFIG_MARS_MIN_SPACE_BASE
and CONFIG_MARS_MIN_SPACE_PERCENT.
You can switch this off by setting to 0.
When the limit is hit, MARS tries to delete the eldest logfile,
when possible, in order to free some space.
Notice: deleting logfiles on a primary which have not yet
been transferred to some secondary is possible, but as a
consequence the secondary may need a full-sync afterwards.
config MARS_PREFER_SIO
bool "prefer sio bricks instead of aio"
depends on MARS
default n
---help---
Normally OFF for production systems.
Only use as alternative for testing.
##### mostly obsolete
config MARS_DUMMY
tristate "MARS dummy brick"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_CHECK
tristate "MARS check brick"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_IF
tristate "interface to a linux device"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_BIO
tristate "interface to blkdev via kernel BIO"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_AIO
tristate "interface to a linux file (Asynchronous IO)"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_SIO
tristate "interface to a linux file, synchronous (currently unused)"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_BUF
tristate "buffer brick (currently unused)"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_USEBUF
tristate "usebuf brick (currently unused)"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_TRANS_LOGGER
tristate "transaction logger"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_SERVER
tristate "server brick"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_CLIENT
tristate "client brick"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_COPY
tristate "copy brick"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
config MARS_LIGHT
tristate "MARS Light main (protoype, will be replaced)"
depends on MARS && MARS_BIGMODULE!=m
default m
---help---
Experimental storage System.
# the following is used as an internal proprocessor symbol
config MARS_HAVE_BIGMODULE
bool