DragonFlyBSD's HAMMER File-System Gets Important Write Performance Boost

Matthew Dillon has discovered an important bug in the DragonFlyBSD kernel's VFS cluster code affecting the HAMMER file-system write performance.

Dillon explained in the commit that landed in DragonFly last week, "A bug in the cluster code was causing HAMMER to write out 64KB buffers in 32KB overlapping segments, resulting in data being written to the media twice."

The impact of this fix is the HAMMER sequential write bandwidth is about doubled. This fix will be found in the upcoming DragonFlyBSD 4.8 release. Meanwhile, there isn't anything new to report on with HAMMER2 -- the most recent HAMMER2 commits were from the beginning of 2017.