Hi,
I'm comparing different configurations of LRC with Reed-Solomon. Specifically I'm comparing the total data read in all OSDs during a reconstruction of a single node (I drop a single OSD and measure until the system is stable again).
While most of the configurations output the desired result, a certain configuration stood out.
The expectation in the following configuration is that RS would generate 40% more reads, however LRC generated 8% more.
RS configuration: k=4, m=6
LRC configuration:
sudo ceph osd erasure-code-profile set myprofile \
plugin=lrc \
mapping=DD_DD_____ \
layers='[
[ "DD_DD_cccc", "" ],
[ "DDc_______", "" ],
[ "___DDc____", "" ],
]' \
ruleset-steps='[
[ "chooseleaf", "osd", 10 ],
]'
RS will always require 4 nodes for reconstruction, however LRC would use less (4 in worst case and 2 in best).
Any thoughts on this matter?
Thanks,
Oleg
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