1. A method for managing file system memory comprising a storage pool comprising respective memory areas for metadata, cache data, and log data, the method comprising: a) starving an initial metadata memory area of a storage pool created for a file system transaction; b) determining on a transactional basis (a) a ratio of metadata memory use to cache data memory use based on input and output operations per second (IOPS) and/or megabytes per second (MBPS) per the file system transaction and (b) an available unused portion of cache data memory replaceable in predetermined slab increments from the cache data memory, wherein slab comprises a contiguous partition of memory; and c) shrinking transactionally the cache data memory per the slab increments based on the ratio of metadata memory use to cache data memory use via cleaning the cache data slabs and attaching the cache data slabs to the metadata memory area for metadata use, which grows the metadata memory area based on the ratio of fragmentation to clean cache data memory despite an absence of a memory bottleneck.