Hi, Right. Could you please describe in few words whet softdeps is ?
Thanks. J-F Le Saturday 05 February 2011 20:11:17, Nick Holland a icrit : > On 02/05/11 09:32, Jean-Francois wrote: > > Hello, > > > > I just read some extracts of a paper, study from Margo Seltzer & Keith A. > > Smith from Harvard university, a comparison of LFS & FFS. > > the paper from 1995?? > > Dude. That's a LONG time ago in the computer world. It is also a very > non-specific "Log-structured file system", which may or may not have any > real-world counterpart here 16 years later (yes, some modern file > systems are "logging" FSs, but...are they descendants of this 1995 LFS? > Or was this LFS a dead-end for real-world reasons that never show up in > academic papers? (I'm sure I could do some more research on this, but > it's your question, not mine :) > > > Basic questions from my side, is FFS-2 better than FFS in the sense of > > dealing with creation of many small files, and is fragmentation less > > than with FFS ? > > Please describe the fragmentation problem you have /observed/... I do a > lot to torment file systems, and never seen anything that looked like a > PROBLEM caused by fragmentation on OpenBSD. If you aren't seeing a real > problem, how can you benefit from optimizing? > > > Are other file systems with some improvement of performance compared to > > FFS available for OpenBSD ? > > Short answer: there are two file systems provided for day-to-day use on > OpenBSD: FFS and FFS2. FFS is the general purpose OS, FFS2 is for very > large file systems which can't be handled by FFS. Nice and simple. > > Other file systems that OpenBSD supports are for cross-system > compatibility, not for "better" anything on OpenBSD, at least at this > time (wouldn't mind seeing a working HAMMER port, of course). > > And...as FFS2 is used for larger file systems, I think it is safe to say > that putting lots of small files on huge file systems is much worse than > putting lots of small files on a few (or a lot) of small file systems. > > However, if you are looking at writing lots of small files, make sure > you you are using softdeps, you will get a very large performance gain > (I'm not talking 10% -- more like 10x!). You may find you get much > better real performance than many logging systems give. > > Nick.
