On May 6, 2014, at 4:41 AM, Hendrik Siedelmann <hendrik.siedelm...@googlemail.com> wrote:
> Hello all! > > I would like to use btrfs (or anyting else actually) to maximize raid0 > performance. Basically I have a relatively constant stream of data that > simply has to be written out to disk. I think the only way to know what works best for your workload is to test configurations with the actual workload. For optimization of multiple device file systems, it's hard to beat XFS on raid0 or even linear/concat due to its parallelization, if you have more than one stream (or a stream that produces a lot of files that XFS can allocate into separate allocation groups). Also mdadm supports use specified strip/chunk sizes, whereas currently on Btrfs this is fixed to 64KiB. Depending on the file size for your workload, it's possible a much larger strip will yield better performance. Another optimization is hardware RAID with a battery backed write cache (the drives' write cache are disabled) and using nobarrier mount option. If your workload supports linear/concat then it's fine to use md linear for this. What I'm not sure of is if it's an OK practice to disable barriers if the system is on a UPS (rather than a battery backed hardware RAID cache). You should post the workload and hardware details on the XFS list to get suggestions about such things. They'll also likely recommend the deadline scheduler over cfq. Unless you have a workload really familiar to the responder, they'll tell you any benchmarking you do needs to approximate the actual workflow. A mismatched benchmark to the workload will lead you to the wrong conclusions. Typically when you optimize for a particular workload, other workloads suffer. Chris Murphy-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
