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On Fri, 27 Apr 2007, Bill Huey wrote: > On Fri, Apr 27, 2007 at 12:50:34PM -0700, Linus Torvalds wrote: >> Oh, well.. Journalling sucks. >> >> I was actually _really_ hoping that somebody would come along and tell >> everybody that this whole journal-logging is stupid, and that it's just >> better to not ever re-write blocks on disk, but instead write to new >> blocks with version numbers (and not re-use old blocks until new versions >> are stable on disk). >> >> There was even somebody who did something like that for a PhD thesis, I >> forget the details (and it apparently died when the thesis was presumably >> accepted ;). > > That sounds a whole lot like NetApp's WAFL file system and is heavily > patented. > > bill Hi SpadFS doesn't write to unallocated parts like log filesystems (LFS) or phase tree filesystems (TUX2); it writes inside normal used structures, but it marks each structure with generation tags --- when it updates global table of tags, it atomically makes several structures valid. I don't know about this idea being used elsewhere. It's fsync is slow too (needs to write all (meta)data too), but it at least doesn't livelock --- fsync is basically: * write all buffers and wait for completion * take lock preventing metadata updates * write all buffers again (those that were updated while previous write was in progress) and wait for completion * update global generation count table * release the lock Maybe Suse will be paying me from this autumn to make more features to it --- so far it works, doesn't eat data, but isn't much known :) Mikulas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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