NAME¶globaliolimits.cfg - global I/O limiting configuration
DESCRIPTION¶The file globaliolimits.cfg contains configuration of the global I/O limiter.
Lines starting with # character are ignored.
limit unclassified <throughput in KiB/s>
limit <group> <throughput in KiB/s>
# 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/.