Date: Tue, 23 Sep 2003 10:31:32 -0700 (PDT) From: Brian Behlendorf <brian@hyperreal.org> To: Doug White <dwhite@gumbysoft.com> Cc: stable@freebsd.org Subject: Re: tuning parameters for parallel access to umass devices? Message-ID: <20030923102845.I10424@fez.hyperreal.org> In-Reply-To: <20030923091649.F86981@carver.gumbysoft.com> References: <20030922120422.W8800@fez.hyperreal.org> <20030923091649.F86981@carver.gumbysoft.com>
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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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