Date: Mon, 7 Oct 1996 23:04:07 -0700 (PDT) From: asami@FreeBSD.ORG (Satoshi Asami) To: bsdscsi@shadows.aeon.net Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: striping/mirroring? Message-ID: <199610080604.XAA01033@silvia.HIP.Berkeley.EDU> In-Reply-To: <199609270938.MAA20281@shadows.aeon.net> (message from mika ruohotie on Fri, 27 Sep 1996 12:38:32 %2B0300 (EET DST))
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* From: mika ruohotie <bsdscsi@shadows.aeon.net> * > If you want to maximize sequential access, you'll need about 6 or 7 * > disks to stripe across them, you'll get to about 28 MB/s with the * > option "I586_FAST_BCOPY". For random access, you'll need more like 30 * > drives through the filesystem to max out the motherboard. * * ok * * only 28 mb/s? isnt it possible to get more speed? That's because there is one memory-memory copy that we can't avoid as long as we go through the filesystem. (Since the memory copy speed is 80MB/s and DMA I/O seems to run at around 60MB/s, we should theoretically be able to get something like 1/(1/80 + 1/60) =~ 35 MB/s but I guess there are some overhead too.) Satoshi
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