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Suggestions for "Buffer size for binary compare" in Preferences > Tweaks

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  • Suggestions for "Buffer size for binary compare" in Preferences > Tweaks

    I am binary comparing an 8TB server and its backup and would like to ask if "Buffer size for binary compare" should be modified from the default value of 65536 bytes in order to speed up this process. Should it be doubled quadrupled or even larger? Does it need to stay as a power of 2 in size? Files being compared are of mixed size (videos 100-4000MB+, songs mostly FLAC 20-40MB and MP3 2-8MB, JPG pictures 2-10MB, and other mixed document files like EXEs from downloaded apps, PDFs, DOCs and general files that might be on your PC). Is the choice of this parameter based on files being compared or does it have to do with how much available memory your machine has? I have one machine that does the backup of the 8TB server most of the time and it has only 16GB of memory. The other machine is a workstation and has 48GB of memory.

  • #2
    We haven't updated the default behavior since before introducing the 64bit builds. It's something we're going to evaluate when we change global defaults for a next major version (BC5). In the meantime, you could knock this up pretty high, as even 16GB is plenty of memory. There would be some diminishing returns eventually, but it's going to be a play with it and see depending on your specific computer running it. You could start with 4MB and increase from there. There are no rules you need to follow for size other than how much you want to dedicate to the binary buffer. Just to be sure it is using the new value, and isn't cached anywhere, I'd suggest a quick full Quit of the application after changing it, and then restart BC4.
    Aaron P Scooter Software

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    • #3
      Aaron,

      Thanks for the quick answer. Sorry for the slow response back. Upped the "Buffer size for binary compare" to 4194304bytes. Seems like this improved the compare speed about 10-20%. My server compare (server is FreeNAS on my gigabit network and my My Book Duo RAID1 backup drive is directly connected to an Intel NUC D54250WYKH). This would show ethernet rates about 100-600Mb/s before increasing the buffer. Now it appears to sustain about 400-700Mb/s more consistently (at least when comparing Music, Videos, and Pictures). Goes slower when EXEs are compared and I'd assume that is my antivirus (it has always slowed on EXEs). Seems like the buffer helps more on groupings of smaller files. It did speed up the large files also. I will try experimenting more (maybe measuring the total time to compare a 500GB folder and then tweaking the buffer value).

      Thanks for the help,

      Rick

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      • #4
        Thanks for the follow up. If you'd like, you can whitelist BCompare.exe or BCompare(process) for your anti-virus, and that might speed things up further.
        Aaron P Scooter Software

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