I ran into an issue with restarting a box after power was cycled with 72 instances of PostgreSQL running. The problem appeared to be that the old pid files, which PostgreSQL never got a chance to clean up, were causing problems when the instances were started or stopped, due to reuse of the pids by instances at different locations. I posted on the hackers list because I thought that there might be a way for PostgreSQL to detect this and prevent the problems. That is not feasible, but people offered three suggestions for how to avoid running into the problem. I'm posting a summary of those solutions here on the admin list, to aid those who may hit the issue and who may not be searching the developer archives for a solution. The original thread is here: http://archives.postgresql.org/pgsql-hackers/2007-08/msg01194.php The three solutions suggested were: (1) Run each instance under a different OS user. (2) Set up a script to clean up old pid files when the OS is booted. (3) Have a script which isn't normally used for managing the instances, but only to clean up the pid files and start the instances after an abrupt failure like a power loss. (For example, we might do something like turn off our existing PostgreSQL instance services under chkconfig and have a "start-all" script to delete pid files and start the services.) Any of the above should keep you out of trouble on a machine with multiple PostgreSQL intances. I do recommend that people in such a situation set themselves up with one of these techniques before they hit a power failure or hardware failure that might expose the issue, since it can be a little confusing in the midst of recovery. (Hmmm... Maybe I'll try to find a good place to put this information in the docs, and submit a doc patch....) -Kevin ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
