Flash controller technology has made great strides in improving reliability and performance, but those improvements are not unique to MLC, just more relevant, since MLC has greater durability and performance concerns. Most of the focus for flash vendors has been on reliability -- correcting errors and improving write cycles -- but SSD controller technology can also be used to improve performance.
The flash controller's contribution to performance typically comes by "shaping" writes so that they can be more efficiently read, and deal with inbound data at a more granular level. An example of granularity can be seen in the garbage collection process, the process that flash controllers go through to pre-clear flash cells for inbound data.
Many garbage collection routines operate during idle periods and tend to manipulate large data sets. If during that process the drive becomes active, this process must be backed out or completed prior to the new activity being handled. By operating at a more granular level, there is less data "in-flight" and the activity can be completed in smaller increments when a drive becomes active.
This was first published in January 2014