document moving GC frequency option in README

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vyzo 2021-07-23 23:05:59 +03:00
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@ -59,6 +59,17 @@ These are options in the `[Chainstore.Splitstore]` section of the configuration:
nodes beyond 4 finalities, while running with the discard coldstore option.
It is also useful for miners who accept deals and need to lookback messages beyond
the 4 finalities, which would otherwise hit the coldstore.
- `HotStoreMovingGCFrequency` -- specifies how frequenty to garbage collect the hotstore
using moving GC.
The default value is 20, which uses moving GC every 20 compactions; set to 0 to disable moving
GC altogether.
Rationale: badger supports online GC, and this is used by default. However it has proven to
be ineffective in practice with the hotstore size slowly creeping up. In order to address this,
we have added moving GC support in our badger wrapper, which can effectively reclaim all space.
The downside is that it takes a bit of time to perform a moving GC (about 40min) and you also
need enough space to house the new hotstore while the old one is still live.
This option controls how frequently to perform moving GC, with the default of 20 corresponding
to about once a week.
## Operation