What happens at 4:00 AM CDT?

[elmwood]

Around 4:00 AM CDT, the SDMB shuts down. Try to access the site, and you get the standard vBulletin database error page. Around 5:00, the site is up and running again.

[Achernar]

From the FAQ:Q: Could [the board] be slow because of board maintenance?
A: Usually board maintenance is at the same time every night - from 03:30 to about 04:15 (Chicago, Illinois, USA time) the database is locked down so that we can capture a consistent backup. Due to the current hardware configuration the old system of modifying the status of the SDMB to present a "down for maintenance" screen is no longer in place.
Any special maintenance done by the Information Services (IS) team at the Chicago Reader office could happen unexpectedly and we (SDMB staff / posters) might not always be notified of it.The server clock is about eight minutes slow, currently, so the downtime starts at 03:38 CT and lasts to about 04:22. In my experience, you'll get a timeout for about the first half of the downtime, and the standard database error page that you mention for the second half.

[elmwood]

Thanks. I missed the FAQ.