Date: Thu, 09 Jun 2011 01:17:13 -0500 From: rendaw <rendaw@zarbosoft.com> To: freebsd-questions@freebsd.org Subject: Re: Intermittent pauses copying from one usb drive to another Message-ID: <4DF06569.9070900@zarbosoft.com>
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Referencing http://lists.freebsd.org/pipermail/freebsd-usb/2011-February/009950.html I'm not sure the best way to go about referencing old threads, but I hope this is acceptable. I'm having the same issue with two 3.5" drives in USB 2.0 enclosures operating in USB 1 mode. Like the OP, I see write activity for 1-5 seconds followed by 1-2 minutes of no activity (I get the same vmstat output). Unlike the OP, I get no error messages in /var/log/messages. I get the same behavior copying files from a local server both scp'ing and tar-over-ssh'ing. Doing tcpdump shows the network traffic completely stop for those pause periods as well (other than some dns or arp or something chatter every once and a while). I did try it on a linux box (just because it was handy) and I got full 1 mb/s speeds with dd (dd if=/dev/whatever of=/dev/null). I get around 800kb/s on FreeBSD doing the same test on either drive. I have the two drives in a ZFS raidz setup, but "top" says I have around 400 of 512mb ram free and the about 2.0 ghz processor is more or less completely unloaded. I tried the same scp to the linux box's internal drive and got no pausing, so I don't think it's an scp/server issue. Assuming this isn't caused by drive message incompatibility, is there some other configuration that could be wrong? Are there some other diagnostics I could try? Thank you very much, Andrew Baxter
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