--- name: "mfschunkserver.cfg" section: "5" platform: "linux" package: "moosefs" version: "4.59.2-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/mfschunkserver.cfg" --- # mfschunkserver.cfg(5) main configuration file for mfschunkserver ## NAME mfschunkserver.cfg - main configuration file for **mfschunkserver** ## DESCRIPTION The file **mfschunkserver.cfg** contains configuration of MooseFS chunkserver process. ## SYNTAX Syntax is: - *OPTION* **=** *VALUE* Lines starting with **#** character are ignored as comments. ### STARTUP OPTIONS Changes in this section require process restart. - **WORKING\_USER** user to run daemon as - **WORKING\_GROUP** group to run daemon as; optional value - if empty then default user group will be used - **SYSLOG\_IDENT** name of process to place in syslog messages; default is mfschunkserver - **LOCK\_MEMORY** whether to perform mlockall() to avoid swapping out mfschunkserver process; default is 0, i.e. no - **LIMIT\_GLIBC\_MALLOC\_ARENAS** limit malloc arenas to given value - prevents server from using huge amount of virtual memory (Linux only, default is 4) - **DISABLE\_OOM\_KILLER** disable out of memory killer (Linux only, default is 1) - **NICE\_LEVEL** nice level to run daemon with; default is -19; note: process must be started as root to increase priority, if setting of priority fails, process retains the nice level it started with - **FILE\_UMASK** set default umask for group and others (user has always 0); default is 027 - block write for group and block all for others - **DATA\_PATH** where to store daemon lock file - **ALLOW\_STARTING\_WITH\_INVALID\_DISKS** when set to one chunkserver will not abort start even when incorrect entries are found in 'mfshdd.cfg' file; default is 0 (do not start with invalid entries) - **CAN\_USE\_MMAP** using mmap for allocation can slightly reduce ram usage and give a silight performance boost, but on certain architectures/kernels can lead to problems - especially on architectures with more than one physical CPU; default is 0 ### RUNTIME OPTIONS Changes in this section require only process reload. - **HDD\_CONF\_FILENAME** alternate location/name of **mfshdd.cfg** file - **HDD\_TEST\_SPEED** Speed of background chunk tests in MB/s per disk (formally entry defined in **mfshdd.cfg**). Value can be given as a decimal number; default is 1.0 - **HDD\_MIN\_TEST\_INTERVAL** prevents from testing chunk integrity when last I/O (including test) was performed less than HDD\_MIN\_TEST\_INTERVAL ago; default is 1 day; for value formatting see TIME - **HDD\_FADVISE\_MIN\_TIME** If possible use posix\_fadvise(POSIX\_DONTNEED) after each chunk test (but only if last I/O operation was performed more than HDD\_FADVISE\_MIN\_TIME ago). Using zero will always perform posix\_fadvise (flush cache) and using negative value will never flush cache after tests. This setting is valid only for systems that support posix\_fadivise; default is 1 day; for value formatting see TIME - **HDD\_LEAVE\_SPACE\_DEFAULT** how much space should be left unused on each hard drive; number format: \[0-9\]\*(\[.\]\[0-9\]\*)?(\[kMGTPE\]\|\[KMGTPE\]i)?B? ; default is 256MiB; examples: 0.5GB, .5G, 2.56GiB, 1256M etc. - **HDD\_REBALANCE\_UTILIZATION** percent of total work time the chunkserver is allowed to spend on hdd space rebalancing; default is 20 - **HDD\_HIGH\_SPEED\_REBALANCE\_LIMIT** maximum simultaneous writes per disk in high speed disk rebalance (0 means use standard rebalance; default is 0) - **HDD\_ERROR\_TOLERANCE\_COUNT**, **HDD\_ERROR\_TOLERANCE\_PERIOD** how many i/o errors (COUNT) to tolerate in given amount of seconds (PERIOD) on a single hard drive; if the number of errors exceeds this setting, the offending hard drive will be marked as damaged; defaults are 2 and 600 - **HDD\_FSYNC\_BEFORE\_CLOSE** enables/disables fsync before chunk closing; default is 0 (off) - **HDD\_SPARSIFY\_ON\_WRITE** enables/disables sparsification (skip leading and trailing zeroz) during writing new block; default is 1 (on) - **HDD\_RR\_CHUNK\_COUNT** how many chunks should be created in one directory before moving to the next one; higher values are better with most OSes caching algorithms, low values lead to more even chunk distribution; default is 10000 which works best in most cases - **HDD\_KEEP\_DUPLICATES\_HOURS** how many hours duplicate chunks should be kept before deleting (default is one week); changing this value and reloading will reset the counter; for value formatting see TIME - **WORKERS\_MAX**, **WORKERS\_MAX\_IDLE** maximum number of active workers and maximum number of idle workers; defaults are 250 and 40 - **SYSLOG\_MIN\_LEVEL** minimum level of messages that will be reported by chunkserver; levels in order of importance: ERROR, WARNING, NOTICE, INFO, DEBUG (default is INFO) - **SYSLOG\_ELEVATE\_TO** reported messages of level lower than set by this option will be elevated to this level (i.e. if **SYSLOG\_MIN\_LEVEL** is set to DEBUG and **SYSLOG\_ELEVATE\_TO** is set to NOTICE, all INFO and DEBUG messages will be sent to syslog as NOTICE ; default is NOTICE) ### MASTER CONNECTION OPTIONS Changes in this section require only process reload. - **LABELS** labels string defined as a set of letters (case insensitive) separated by coma or semicolon; default is empty - no labels - **BIND\_HOST** local address to use for master connections; default is \*, i.e. default local address - **MASTER\_HOST** MooseFS master host, IP is allowed only in single-master installations; default is mfsmaster - **MASTER\_PORT** MooseFS master command port; default is 9420 - **MASTER\_CONTROL\_PORT** (pro only) MooseFS master control port; default is 9419 - **MASTER\_TIMEOUT** timeout in seconds for master connections (if not 0); If this value is zero then chunkserver sets it initially to 10 and asks master for this value. default is 0 (ask master). - **MASTER\_RECONNECTION\_DELAY** delay in seconds before trying to reconnect to master after disconnection (default is 5) - **AUTH\_CODE** authentication string (used only when master requires authorization) - **CHUNKS\_PER\_REGISTER\_PACKET** maximum number of chunks system will try to put in a single register message (default is 1000, limits 100-10000) ### CLIENTS CONNECTION OPTIONS Changes in this section require only process reload. - **CSSERV\_LISTEN\_HOST** IP address to listen on for client (mount) connections (**\*** means any) - **CSSERV\_LISTEN\_PORT** port to listen on for client (mount) connections (default is 9422) ## NOTES ### TIME For config variables that define time without requiring a single, specific unit, time can be defined as a number of seconds (integer) or a time period in one of two possible formats: first format: #.#T where T is one of: s-seconds, m-minutes, h-hours, d-days or w-weeks; fractions of seconds will be rounded to full seconds second format: #w#d#h#m#s, any number of definitions can be omitted, but the remaining definitions must be in order (so #d#m is still a valid definition, but #m#d is not); ranges: s,m: 0 to 59, h: 0 to 23, d: 0 t o 6, w is unlimited and the first definition is also always unlimited (i.e. for #d#h#m d will be unlimited) Notice! For variable **HDD\_KEEP\_DUPLICATES\_HOURS** only h,d and w time units are accepted and a value without a time unit is treated as hours; fractions are rounded to full hours. Examples: 1\.5h is the same as 1h30m, is the same as 90m, is the same as 5400s, is the same as 5400 2\.5d is the same as 2d12h, is the same as 60h; 1d36h is not a valid time period (h is not the first definition, so it is bound by range 0 to 23) 1\.03m is the same as 62s (61.8 seconds will be rounded up to 62) ## COPYRIGHT Copyright (C) 2026 Jakub Kruszona-Zawadzki, Saglabs SA This file is part of MooseFS. MooseFS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2 (only). MooseFS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see \. ## SEE ALSO [**mfschunkserver**(8)](/mfschunkserver/8.md), [**mfshdd.cfg**(5)](/mfshdd.cfg/5.md)