Posted Oct 11, 2012 19:16 UTC (Thu) by skitching (subscriber, #36856)
Parent article: An f2fs teardown
Thanks for the great analysis Neil.
Unfortunately, it is sad to see that f2fs is *so* coupled to an underlying FTL. I presume that where you say "leaves it to the FTL", this means that f2fs is simply rewriting data at a fixed address, and relying on the FTL to relocate that address to perform wear-leveling. And given that flash is supposed to be efficient at random writes (in units of an erase block) it is a shame that f2fs spendsg so much effort grouping writes into larger operations to help the FTL layer perform.
So we have a choice of filesystems that only work well on "raw" flash (jffs2, ubifs, logfs) or a filesystem that only works well on managed flash (f2fs).
AIUI, FTL is a solution invented to make it possible to put filesystems like FAT32 onto a flash device without quickly killing it. Are we really still going to be stuck with FTL decades from now?
If the industry is going to provide a "raw" interface to removable flash media in the near future, then f2fs will only be a short-term solution, yes? And interestingly, Samsung are exactly the people who could get a "raw flash interface" happening...