On Tue, Jan 11, 2011 at 2:27 PM, Jim Hu <[email protected]> wrote: > As the number of wikis we host increases, I worry about our single mysql > server becoming a bottleneck. I assume that by modifying $wgDBserver in > the different copies of LocalSettings.php, I can point each wiki to a > different port that is running a different instance of mysql. > > But is this worth doing? My concern is that when we do db intensive stuff > on wiki A, wikis B...X will underperform. >
In most cases, the only reason to run multiple MySQL instances is because they're running on separate machines. It'll almost certainly be much better to run only a single MySQL daemon instance per host. Multiple instances on the same host would be doing the same work *plus* additional work, as they'd each individually be maintaining their own in-memory data caches, file access, etc. If your memory sizes are too large, you'll hit swap and performance will be completely destroyed; if your memory sizes are too small, you won't be using the full capacity of the machine. A single instance will generally be able to much more reasonably partition resources according to usage. (A database that is never used need not take up any memory; a database that is hugely used can use as much key cache memory etc as it needs -- but must negotiate for that space with the other things being done.) -- brion _______________________________________________ MediaWiki-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/mediawiki-l
