Date: Mon, 2 Jul 2012 21:07:57 +0100 From: maxim naumov <muxx.mailinglists@gmail.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: freebsd-usb@freebsd.org Subject: Re: Seagate FreeAgent GoFlex 1.5TB external HDD problems Message-ID: <CAGG2Ak%2Bqi%2BPnyAJbxfS%2B_wuQ3kcXH5cu8EyBnpBSu-69ksFL3Q@mail.gmail.com> In-Reply-To: <201206251700.39759.hselasky@c2i.net> References: <CAGG2Ak%2BXmWvCb3PQoqPXAW7iC0PAQ=GNV79MhhGHjLO4GmWgdw@mail.gmail.com> <201206241533.08745.hselasky@c2i.net> <CAGG2Ak%2Bz3%2B=jcZ6Znws9BLCZX=Ja%2B24n8MLeWfLNO-%2BoJseVDQ@mail.gmail.com> <201206251700.39759.hselasky@c2i.net>
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ok, done some more testing and measured throughput FreeBSD vs. GNU/Linux as you suggested: # dd if=/dev/da0s1 of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes transferred in 33.181306 secs (32359842 bytes/sec) and # dd if=/dev/sdb1 of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB) copied, 33.2969 s, 32.2 MB/s I was doing more testing with dt, specifying different maximum and minimum block sizes for random transfers. the curious thing is that I could not fail it if the maximum block size is up to 16k. 32k and higher eventually kills it. it seems to require random transfer size to fail. the filesystem driver will do the same. doing just dd/dt with a specified bs works fine. also I haven't seen it fail with a transfer size smaller than 32k before. could this be something to do with the USB transfer size of 64k (32k of data plus umass command)? /max
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