-Greg
On Monday, November 2, 2015, Loris Cuoghi <lc@xxxxxxxxxxxxxxxxx> wrote:
On Monday, November 2, 2015, Loris Cuoghi <lc@xxxxxxxxxxxxxxxxx> wrote:
Le 02/11/2015 12:47, Wido den Hollander a écrit :
On 02-11-15 12:30, Loris Cuoghi wrote:
Hi All,
We're currently on version 0.94.5 with three monitors and 75 OSDs.
I've peeked at the decompiled CRUSH map, and I see that all ids are
commented with '# Here be dragons!', or more literally : '# do not
change unnecessarily'.
Now, what would happen if an incautious user would happen to put his
chubby fingers on this ids, totally disregarding the warning at the
entrance of the cave, and change one of them?
Data shuffle? (Relative to the allocation of PGs for the OSD/host/other
item?)
A *big* data shuffle? (ALL data would need to have its position
recalculated, with immediate end-of-the-world data shuffle?)
Nothing at all? (And the big fat warning is there only to take fun on
the uninstructed ones? Not plausible...)
Give it a try! Download the CRUSHMap and run tests on it with crushtool:
$ crushtool -i mycrushmap --test --rule 0 --num-rep 3 --show-statistics
Now, change the map, compile it and run again:
$ crushtool -i mycrushmap.new --test --rule 0 --num-rep 3 --show-statistics
Check the differences and you get the idea of how much has changed.
Wido
Thanks Wido ! :)
_______________________________________________Thanks !_______________________________________________
Loris
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