I am running a postgres 8.4.5 server on the linux 220.127.116.11 kernel on an 8 disk raid array with an LSI controller.
Most of the tables are around 1GB or less.
I know that XFS uses allocation groups (AG) to achieve I/O parallelism.
My first question is, does this mean that if two tables are in the same AG, all I/O requests are queued to both of them if either is being read from/written to?
If so, I assume I would want to spread my tables across as my allocation groups as possible, correct? Wouldn't this ensure that multiple users querying different tables would get the best performance?