main/4985/iproto txn.cc:214 W> too long WAL write: 12.174 sec
I’m getting the error above. What could be the reason?
A. It looks like your WAL is not keeping up with the load. Tarantool complains about WAL writes when it takes more than 0.5 seconds to commit a change. If this is periodic, it's most likely that something else is going on in parallel.
If you want to fix it, you need to know what's causing it. This can be either due to shortage of I/O or CPU. For example, you could have an inefficient Lua procedure which is taking all the CPU. You can pinpoint the reason only by looking at what's going on when Tarantool is complaining.