Arvados

From a practical perspective, it seems like Arvados 2.7.0 represents a "flag day" transition from using the old database-backed Crunch logs to using the new WebDAV log API.

• Workbench 2 no longer gets these logs from the database at all, using the new endpoint exclusively.
• With that, I don't believe any client code shipped with Arvados uses the old system anymore.
• The default configuration for LimitLogBytesForJob is now 0, which effectively stops Crunch from writing old-system logs.

I think this transition is underdocumented.

• The upgrade notes should explain the transition. If administrators have LimitLogBytesForJob configured, they should normally remove that and rely on the default setting. If they have custom client code reading the old logs, they can configure it to a higher value for now, but the old logging system is deprecated and they should work on porting those clients to use the new logging API.
• Are there other places in the documentation we should note the deprecation of the old logging system? Maybe in the logs API documentation?
• The third bullet point on /doc/admin/logs-table-management.html should be reframed to explain this is about the old logging system and on its way out. (Even administrators who have upgraded and transitioned to the new logging system may find old logs in their database they're wondering about, so we should leave the explanation in for now.)