globaliolimits.cfg - global I/O limiting configuration
The file globaliolimits.cfg
contains configuration of the global I/O
Lines starting with #
character are ignored.
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.
I/O limiting is disabled, no limits are enforced.
All clients are unclassified
and share 1MiB/s of bandwidth.
limit /a 1024
Clients in the blkio /a
group are limited to 1MiB/s, no other
clients can perform any I/O.
limit unclassified 256
limit /a 1024
limit /b/a 2048
is allowed to transfer 1MiB/s, while
gets 2MiB/s. Clients from other groups (e.g. /b
) are considered unclassified
256KiB/s of bandwidth.
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
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
The ratio of bandwidth being wasted due to this phenomenon shouldn’t
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 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/.