Put your write ahead logs on a mirrored set of ssds as long as your write patterns can handle a build up of logs before archiving to slower storage. This gets t

Put your write ahead logs on a mirrored set of ssds as long as your write patterns can handle a build up of logs before archiving to slower storage. This gets the fsync out of the way so the application will block for a shorter amount of time. Postures relies heavily on disk cache, so be sure to tune shared memory small enough to allow the kernel to cache commonly used disk pages. ZFS on FreeBSD and OpenSolaris has the ARC as a second level of caching between disk cache and slow disk IO. Te Adaptive Readahead Cache can take advantage of some ssds to up access for your hotspots.