On Thu, Aug 18, 2016 at 7:24 PM, Eduardo Horvath <[email protected]> wrote: > > LFS writes the metadata at the same time, in the same place as the data. > No synchronous writes necessary.
As I understand LFS needs to do synchronous writes when there is metadata operations (directories)/fsync operations involved. Instead of writting a full segment (1 MB per default), it writes a "small segment". It kills performance in RAID 5/6, because the write isn't a full stripe: you have to read all the disks, for calculate the new parity 1 write on raid of x disks= x reads + 2 writes (data + parity). The NVRAM memory solves this problem as buffer/ write cache. > > The problem is that LFS is less a product than a research project: Yes I know this. But it seems that it was near stable in previous versions: 1.6 and 4.0 of NetBSD. David Holland is slowly solving some of these problems (most of a MP kernel). I also wan to to give my small help. > > Anyway, hacking on LFS is lots of fun. Enjoy! This is true. I want to contribute to a great project as NetBSD.
