Re: tuning parameters for parallel access to umass devices?

From: Brian Behlendorf (brian_at_hyperreal.org)
Date: 09/23/03

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    Date: Tue, 23 Sep 2003 10:31:32 -0700 (PDT)
To: Doug White <dwhite@gumbysoft.com>

    On Tue, 23 Sep 2003, Doug White wrote:
    > On Mon, 22 Sep 2003, Brian Behlendorf wrote:
    >
    > > It looks like copying files over USB to a umass device causes other I/O
    > > attempts to be blocked for an unreasonable (10-20 seconds) amount of time.
    > > Here's the device in question:
    >
    > On the volume being copied to, or another volume?

    On the volume being copied to (or from) - that is, while moving a big file
    to/from such a device, doing an 'ls' or other operations on that device
    are delayed.

    > > da2: 650KB/s transfers
    >
    > Don't forget that this isn't much faster than a floppy disk, and flash I/O
    > is pretty slow anyway.

    Granted. This is do a hard drive that can definitely handle it - mounting
    the same drive (Maxtor 5000XT) over firewire works brilliantly - the
    full 50MB/s transfer speed, and parallel operations are fine. I just
    don't have fw everywhere.

            Brian

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