On Jan 31 2008 22:17, Evgeniy Polyakov wrote: > >POHMELFS stands for Parallel Optimized Host Message Exchange >Layered File System. It allows to mount remote servers to local >directory via network. This filesystem supports local caching >and writeback flushing. >POHMELFS is a brick in a future distributed filesystem. A brick is usually something that is in the way - Or you also say "the user has bricked his machine" when it's quite unusable :) Hope you did not mean /that/. >This set includes two patches: > * network filesystem with write-through cache (slow, but works with > remote userspace server) > * hack to show how local cache works and how faster it is compared > to async NFS (see below). hack disables writeback flush and > performs local allocation of the objects only. > >Now, some vaporware aka food for thoughts and your brains. > >A small benchmark of the local cached mode (above hack): > >$ time tar -xf /home/zbr/threading.tar > > POHMELFS NFS v3 (async) >real 0m0.043s 0m1.679s > >Which is damn 40 times! Needs a bigger data set to compare. But what is much more important: does it use a single port for networing, or some firewall-unfriendly-by-default multiple dynamic-port-allocation like NFS? >Next task is to think about how to generically solve the problem with >syncing local changes with remote server, when remote server maintains inodes with >completely different numbers. >This, among others, will allow offline work with automatic syncing after reconnect. What will happen when both nodes change an inode in disconnected state? Which inode wins out? >This is not intended for inclusion, CRFS by Zach Brown is a bit ahead of POHMELFS, >but it is not generic enough (because of above problem), works only with BTRFS, >and was closed by Oracle so far :) btrfs is all we need :p Where's the parallelism that is advertised by the "POH" in pohmelfs? - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
