Date: Mon, 23 Jul 2012 09:40:20 +0200 (CEST) From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> To: Jakub Lach <jakub_lach@mailplus.pl> Cc: freebsd-questions@freebsd.org Subject: Re: "da0: 40.000MB/s transfers" What was rationale behind pegging USB 2.0 at 40MB/s? Message-ID: <alpine.BSF.2.00.1207230937150.7616@wojtek.tensor.gdynia.pl> In-Reply-To: <1342994216549-5729035.post@n5.nabble.com> References: <1342992043358-5729028.post@n5.nabble.com> <alpine.BSF.2.00.1207222331130.4614@wojtek.tensor.gdynia.pl> <1342994216549-5729035.post@n5.nabble.com>
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> dd if=/dev/zero of=/dev/da0 bs=1 to 15M > > runs, 13-14MB/s from actual files copied > in mc to flash and 36-39MB/s file copied > from flash to hdd in mc. > > dd if=/dev/da0 of=/dev/zero bs=15m > > gives 33MB/s read. and this is incredibly high as of any pendrive. Consider few things: - pendrive flash mappers are incredibly dumb, they work in usable speed when you do linear write only. - today lies are standard. never believe in stated performance unless you measure it. > even recognized in FreeBSD as device. what i do with any pendrive: dd if=/dev/zero of=/dev/da0 bs=64k count=1 newfs_msdosfs /dev/da0 (if i want FAT filesystem) partition table is not needed in any OS, including Windows starting from XP. msdosfs in FreeBSD isn't high performance too. try writing small amount of huge files.
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