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Benchmarks Of Btrfs RAID On Four Samsung 970 EVO NVMe SSDs

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  • #11
    It might also make sense to try setting NOCOW ['chattr +C'] on the files/directories used for database testing, as this would normally be a recommended production configuration due to the impact of fragmentation (although whether most SQLite databases are set like that is an interesting question).

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    • #12
      I am waiting for the comparison with ZFS !

      Also, for single and dual drive, please include benchmarks of on-board m.2 slots to compare with the performance of the XPANDER-AERO. Just in case that there is performance degradation with the pcie board.

      Also, do you have intel optane drives on hand ? That would also be nice to see !

      Thanks

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      • #13
        I am also waiting for the ZFS benchmark.

        Also, could the single and dual nvme config be tested on the on-board m.2 slots ? Just to make sure the pcie card doesn't bring performance loss (shouldn't, but not couldn't).

        Thanks

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        • #14
          Michael could you modify the database tests on Btrfs to apply the C attribute on the test directory using chattr, before initiating the test? It's to disable the CoW system for that directory and to my understanding it's the best approach to handling these directories on a CoW filesystem. It would be interesting to see what the results would be.

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          • #15
            I do use btrfs a lot, but actually always with noadata and with chattr +C for databases and VM's. I think the test with defaults is quite unimportant, but at least there are some numbers to look at ;-)

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            • #16
              Originally posted by schmidtbag View Post
              Haha I meanwhile am just interested in where I can get my hands on the XPANDER card without buying the motherboard. That thing intrigues me.
              Asrock has a similar card which can actually be found on sale somewhere, "ASRock ULTRA QUAD M.2 CARD", also ASUS has "ASUS Hyper M.2 x16" but imho the Asrock one is better as it can fit longer SSDs and has a better fan and thermal pads.

              MSI seems to be a latecomer.

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              • #17
                Originally posted by R41N3R View Post
                I do use btrfs a lot, but actually always with noadata and with chattr +C for databases and VM's. I think the test with defaults is quite unimportant, but at least there are some numbers to look at ;-)
                I disagree, I think the defaults are very important. This is what people can expect from most workloads, and really this is how things are meant to be.
                However, it would be interesting to also adapt certain "tuneings" that many BTRFS users most certainly will apply such as disabling data-cow and isolating such parts of the filesystem (subvolumes). Once you got per. subvolume "raid" levels things really start to get interesting as well.

                I also think that I should point out that some of the tests being done on BTRFS suffers from the fact that BTRFS choose what mirror to use based on the PID (process identifier). So let's say you run some sqlite read performance test from one process, for example with PID: 5432 then BTRFS will always pick mirror number 2 unless there is a read error. If you at the same time in parallell run a process with PID 4321 then you would read from both copies and get a significant performance increase.
                Now , this is not (contrary to popular belief) much different than MDRAID, but you really have to understand how BTRFS work to interpret the benchmark results as well.

                The good thing is that there has been patches posted that will make BTRFS pick a storage device based on the queue. The sad thing is that these patches has not been accepted (yet). Once those (or similar patches) gets merged the defaults would be even more interesting to watch

                http://www.dirtcellar.net

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