This one is going out to the world in general, because it took me 2 hours of googling to find it, and I want to lessen some poor other slobs pain…
MySQL , in this case on a Debian Etch (stable) install, has a limit set on the number of files that can be opened in the mysqld server. Apparently when you start getting close to this limit, like doing something that opens a LOT of tables at once, you start bumping into it. This article describes how to fix this.
For me this happened when trying to do a ‘mysqldump’ of the Drupal 5.0 installation we have. Drupal 5 can put all the sites tables into a single database instance. Of course, that means when you do the mysqldump, if you have a large number of sites, you’re dumping a large number of tables.
Like, say, 530.
In the default configuration, this causes mysqldump to barf with an unhelpful message like this: