DragonFly kernel List (threaded) for 2008-02
Re: HAMMER update 06-Feb-2008
Matthew Dillon wrote:
* Implement the filesystem as one big huge circular FIFO, pretty much
laid down linearly on disk, with a B-Tree to locate and access data.
* Random modifications (required for manipulating the B-Tree and marking
records as deleted) will append undo records to this FIFO and the only
write ordering requirement will be that the buffers containing these
undo records be committed before the buffers containing the random
modifications are committed.
This sounds quite like LFS now. LFS however split the volume in smaller
blocks which could be "used", "empty" or "open", IIRC. Their background
cleaner then could push remaining data from used blocks to a currently
open one, marking the block "empty" after that, allowing the FS to write
to the blocks again.
They always had problems with the cleaner, I think.
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