Iterating of every file not just once in a while but frequently, maybe that was an idea easy and cheap to implement when nodes were at 500GB.
But now with nodes at 15TB this is pure madness. And on top the frequent restarts after updates and everything starts all over from the start except when data was kept in RAM only like with the Bloomfilter until recently fixed. Plus independent from the load aka customer usage of the node it gets hammered by filewalkers, database accesses and all.
And the thing is, you should use what you have. So it should basically run without issues on anything without the need to invest into SSDs, RAM or whatever.
I agree, all of that sounds totally crazy.
But this
seems to be a good thing:
1556872 – iostat %wrqm coloring misleading
The attention-marking is misleading: a number approaching 100% is not at all a bad thing -
in fact it’s good that the system can reduce the number of IOPS by merging sequences.
It’s far from clear that any range of values in this field can be considered as either
acceptable or bad.
Edit: We are looking very much forward to have this stop and resume feature ready and deployed:
save-state-resume feature for used space filewalker
Can’t stress enough how much this is needed!