FreeBSD MySQL still WAY slower than Linux

[Roman Neuhauser]

# olli at lurza.secnetix.de / 2005-06-21 16:51:10 +0200:
> For accurate measurements and comparisons, you have to make
> sure to use _exactly_ the same physical location on the
> disk.

    No you don't. You want to make a side-by-side comparison
    of two products, and if one of them underperforms, it just
    underperforms. You cannot use a poor location selection
    strategy in the driver as an excuse for poor operation.

    In all honesty, I'm getting somewhat irritated by all the
    "dd is meaningless performance measurement tool, use something
    real" and similar arguments: dd is a real command for real
    work, and if it shows abysmal performance of sequential writes,
    then there's a problem.

> But then again -- as others have already mentioned, serial
> write speed is not the most important factor for database
> performance (although the WAL journal files of advanced
> transactional databases like PostgreSQL are written in a
> sequential way), so the usefulness of this "benchmark" is
> very debatable.

    Well, how about a few GB large table physically ordered
    ("clustered") on a column, that goes through repeated sequential
    scans? This *is* a real-world situation, and every bit of speed
    counts (the live server I'm talking about has the database on SCSI
    disks, but development machines frequently differ).

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