MySQL master/slave replication delay
he has a large php/mysql driven website running from three servers. the first has apache that handles the php and serves all the images. there's also two MySQL servers. the master mysql server handles all the write/update querys and the slave MySQL server handles all the reads.
the two mysql servers are setup for replication. at off-peak times, there is no delay. however, during peak traffic, the slave server gets as much as 10 mins behind. this becomes a MAJOR problem with things like user comments (so it gets added to the master/write server), but then not seeing their post (not showing up on the slave/read sever) for up to 10 mins.
all three machines are on the same rack and it's pretty safe to rule out hardware issues. also, even during peak traffic, neither mysql server really gets what i'd consider an 'unsafe' load so i don't think it's just backlogging the updates unless there is some way to improve the priority of the "replication update" over the other queries.
it's been that way as long as they've had the severs and the guy who originally setup the replication isn't available anymore. anybody have an ideas on where to start looking, or tests to run to maybe determine where the problem is?
