I don't think I am someone "in-the-know" but here are a few more points:
1)
including more of the info specified in
IMPORTANT: Improving issue management
would probably be helpful.
Minimally what version of orientdb you are using.
Telling more about the shape of your data, properties and indices could be helpful too.
2)
This page of the doc describes the WAL stuff and says how to disable it.
This page of the doc has more performance help
3)
My previous post established that the .sbc files are probably indices of some sort.
looking at the files in a database, I see examples of these sbc files:
./multi/collections_13.sbc
inspecting the schema for that db shows I have some EMBEDDEDSET properties and an index on some.
I do not want to do this now but you could experiment with creating different dbs, for example:
i) create one without collection-like properties (no EMBEDDEDSET, etc)
ii) create one with collection-like properties (EMBEDDEDSET, etc)
iii) create one with collection-like properties and create and index
iii) add a large amount of data to some of the previous dbs
and see how that affects the file existence/sizes. do some debugging/science!
4)
You can take a look at the code to try to figure more stuff out, this file might be relevant:
5) double/triple posting rapidly is rude!