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GLOBALIOLIMITS.CFG(5)					 GLOBALIOLIMITS.CFG(5)

NAME
       globaliolimits.cfg - global I/O limiting	configuration

DESCRIPTION
       The file	globaliolimits.cfg contains configuration of the global	I/O
       limiter.

SYNTAX
       Syntax is:

       option value

       Lines starting with # character are ignored.

OPTIONS
       Configuration options:

       subsystem <subsystem>
	   The cgroups subsystem by which clients are classified. If left
	   unspecified,	all clients are	considered unclassified	(see below).

       limit unclassified <throughput in KiB/s>
	   This	is a special entry for clients that don't match	any group
	   specified in	configuration file or for all clients if subsystem is
	   unspecified.	If this	entry is unspecified and subsystem is
	   unspecified as well,	I/O limiting is	disabled entirely. If this
	   entry is unspecified	but subsystem is specified, unclassified
	   clients are not allowed to perform I/O.

       limit <group> <throughput in KiB/s>
	   Set limit for clients belonging to the cgroups group	<group>. In
	   LizardFS, subgroups of <group> constitute independent groups; they
	   are not allowed to use <group>'s bandwidth reservation and they
	   don't count against <group>'s usage.

EXAMPLES
	   # empty file

       I/O limiting is disabled, no limits are enforced.

	   limit unclassified 1024

       All clients are unclassified and	share 1MiB/s of	bandwidth.

	   subsystem blkio
	   limit /a 1024

       Clients in the blkio /a group are limited to 1MiB/s, no other clients
       can perform any I/O.

	   subsystem blkio
	   limit unclassified 256
	   limit /a   1024
	   limit /b/a 2048

       The blkio group /a is allowed to	transfer 1MiB/s, while /b/a gets
       2MiB/s. Clients from other groups (e.g. /b, /z, /a/a, /b/z) are
       considered unclassified and share 256KiB/s of bandwidth.

TUNING NOTES
       Global I/O limiting is managed by the master server. Mount instances
       reserve bandwidth allocations from master when they want	to perform I/O
       to chunkservers.

       To avoid	overloading the	master under heavy traffic, mounts try to
       predict their future usage and reserve at once all the bandwidth	they
       will for	the next renegotiation period (see mfsmaster.cfg(5)).

       Such reservation	are wasted if the traffic at given mount instance
       suddenly	drops.

       The ratio of bandwidth being wasted due to this phenomenon shouldn't
       exceed fsp/b, where:

	   f is	the frequency of sudden	traffic	drops in the whole installation	(in 1/s)
	   s is	the average size of such drop (in KiB/s)
	   p is	the renegotiation period (in s)
	   b is	the bandwidth limit (in	KiB/s)

       This applies to each group separately, because groups reserve their
       bandwidth independently from each other.

COPYRIGHT
       Copyright 2008-2009 Gemius SA, 2013-2015	Skytechnology sp. z o.o.

       LizardFS	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 3.

       LizardFS	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 LizardFS. If not, see http://www.gnu.org/licenses/.

SEE ALSO
       mfsmaster.cfg(5)

				  08/29/2020		 GLOBALIOLIMITS.CFG(5)

NAME | DESCRIPTION | SYNTAX | OPTIONS | EXAMPLES | TUNING NOTES | COPYRIGHT | SEE ALSO

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