Date: Tue, 3 Jul 2012 08:08:23 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: maxim naumov <muxx.mailinglists@gmail.com> Cc: freebsd-usb@freebsd.org Subject: Re: Seagate FreeAgent GoFlex 1.5TB external HDD problems Message-ID: <201207030808.23509.hselasky@c2i.net> In-Reply-To: <CAGG2Ak%2Bqi%2BPnyAJbxfS%2B_wuQ3kcXH5cu8EyBnpBSu-69ksFL3Q@mail.gmail.com> References: <CAGG2Ak%2BXmWvCb3PQoqPXAW7iC0PAQ=GNV79MhhGHjLO4GmWgdw@mail.gmail.com> <201206251700.39759.hselasky@c2i.net> <CAGG2Ak%2Bqi%2BPnyAJbxfS%2B_wuQ3kcXH5cu8EyBnpBSu-69ksFL3Q@mail.gmail.com>
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On Monday 02 July 2012 22:07:57 maxim naumov wrote: > 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)? Hi, For High Speed, the software size limit is 64KBytes, because many devices don't support more. --HPS
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