Date: Mon, 18 May 2009 13:29:48 -0700 From: Yuri <yuri@rawbw.com> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: freebsd-questions@freebsd.org Subject: Re: What is the highest hard drive read/write speed you were able to achieve by entire disk mirroring or striping? Message-ID: <4A11C53C.3090008@rawbw.com> In-Reply-To: <alpine.BSF.2.00.0905060818230.28367@wojtek.tensor.gdynia.pl> References: <4A00B3FA.5050905@rawbw.com> <alpine.BSF.2.00.0905060818230.28367@wojtek.tensor.gdynia.pl>
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Wojciech Puchar wrote: >> I am seeing 85MB/s as a speed of a single Hitachi 1TB HD. >> How high can you go by mirroring or striping 2, 3, 4 harddrives? > > mirroring - the same, just with 2 processes reading both can get the > bandwidth. make sure you use -s high enough (like 1048576) doing > gmirror label > > stripping - the same, or 2,3,4 times, depends how you configure. > for highest transfer and lowest concurrency (you mostly read huge > files with one process) - use small stripe size. > for lowest transfer (=1 disk) and highest concurency - use very huge > stripe size like 512MB, so simply different process reading different > things can hit different drives, but each I/O isn't spread. So if I will put 6 hard drives with stripping each of them is 85MB/s (in the beginning sectors) I will get 6X85MB/s=4.08Gb/s? Is it reasonable to expect this kind of speed? Something tells me that there will be some other factors like bus speed that would potentially limit the speed in such case. Yurihome | help
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