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Comment Re:No defrag! (Score 1) 370

Yes. Alas, this is a consequence of ZFS's COW (copy on write) design.

In a filesystem like EXT3, if you open a file, seek to some offset, and write new data, EXT3 will write the new data to the existing disk block in place. ZFS, however, will allocate a new block for that offset (copy on write), write the modified data to it, and update the block chain. The result is that it's apparently very easy to badly fragment a ZFS file (do a Google search for "ZFS fragmentation" to see various stories and tests people have written).

You can apparently mitigate the problem by occasionally copying the entire affected file -- Oracle's own whitepaper on the subject apparently reads, "Periodically copying data files reorganizes the file location on disk and gives better full scan response time."

Bottom line: ZFS is not a panacea, nor is it simple. There are myriad options, and trade-offs to all of them.

Comment Re:Lua[0]? (Score 1) 729

Arrays in C++ start at 0. I'm pretty sure you can set a pointer into the middle of the array in C++ and do this by indexing the pointer. I know you can do it in C -- a couple companies ago I deployed something that did that into production code, mainly to keep the design review board on their toes. They weren't, and it got deployed that way. I thought it made more sense that way anyway, so I never mentioned it. It's entirely possible it's already confused the hell out of a code maintenance guy, but hopefully he'll think it makes more sense that way too.

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