Date: Thu, 01 May 1997 17:16:13 -0600 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: "Jin Guojun[ITG]" <jin@george.lbl.gov> Cc: hardware@FreeBSD.ORG Subject: Re: 53C875 UW SCSI-3 adapter Message-ID: <199705012217.QAA22846@pluto.plutotech.com> In-Reply-To: Your message of "Thu, 01 May 1997 14:15:34 PDT." <199705012115.OAA10970@george.lbl.gov>
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>Under both 2.1.7 and 2.2.1, the 53C875 ultra-wide SCSI-III host adapter, made >by J Bond Computer Systems (JDC5075), has the same performance as the 53C825, >which is just a wide SCSI host adapter, about 18 MBytes/sec. >The disk drive I used are Seagate BARRACUDA 9 (ST19171W) , which seagate >claims that can go 40 MBytes in sychronous-transfer mode. > >Has someone experimented the throughput of 53C875 ultra-wide SCSI-III host >adapter with any wide or ultra-wide drives? > >-Jin If you only have a single drive on the bus, the difference between 20MB/s and 40MB/s transfer rates on the bus will not make much of a difference in your benchmarks. The bus is not your bottleneck. The media transfer rate is. There are very few drives that can transfer to/from the media at rates above 10MB/s. In fact, the fastest I've seen a Seagate 'Cuda (this was a 4gig drive) transfer into cache was 15MB/s on an ultra/narrow bus with no other devices on it. -- Justin T. Gibbs =========================================== FreeBSD: Turning PCs into workstations ===========================================
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