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Xref: sserve comp.arch:27896 comp.unix.bsd:7513 comp.os.linux:14883 Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!agate!doc.ic.ac.uk!uknet!cf-cm!news From: spxpmf@thor.cf.ac.uk (Phillip Fayers) Newsgroups: comp.arch,comp.unix.bsd,comp.os.linux Subject: Re: IDE faster than Mips SCSI disk Message-ID: <13481.9211061131@thor.cf.ac.uk> Date: 6 Nov 92 11:31:23 GMT References: <1992Nov6.033942.21194@ntuix.ntu.ac.sg> Sender: news@cm.cf.ac.uk (Network News System) Organization: Physics Dept. University of Wales, Cardiff Lines: 52 X-Mailer: Cardiff Computing Maths PP Mail Open News Gateway In article <1992Nov6.033942.21194@ntuix.ntu.ac.sg> eoahmad@ntuix.ntu.ac.sg (Othman Ahmad) writes: |These figures are not meant to be a thorough study. More of a provocation |for more soul searching. The widespread belief that SCSI-2 is "defininely |faster than IDE" is questionable, in fact under some circumstances, entirely |false. | The results are not surprising for those who study the technical |specs of these disks. IDE has more potential for high speed because of its |lack of protocaol overhead. Its closeness to the disk also make it very |reliable and efficient. | There are advanced disks which can do simultaneour multiple-head reads, |but these techniques can also be used for IDE as well. | IDE is just a simple interface definition, just like SCSI-2, but IDE, |is optimised for HARD DISKS, SCSI is not. SCSI is more general purpose. | |The mips machine under test runs on ultrix. Although it has up to 10Gbyte |of hard-disk, it is not so heavily loaded. We only use it for email and |news feed. Fragmentation can be severe because I cannot even have 32 |megabyte free space in /usr/tmp , only 30 Mbytes. | |Writing the 30 Megabyte file, 'iozone.tmp'...91.000000 seconds |Reading the file...49.000000 seconds | |IOZONE performance measurements: | 345684 bytes/second for writing the file | 641985 bytes/second for reading the file |**************************************************************************** |This PC machine runs on 386bsd. Using 1 megabyte test file it is faster than |a similar 486/50Mhz EISA SCSI-2 hard-disk. | |486/33 Maxtor 7120 200Mbyte | |Writing the 32 Megabyte file, 'iozone.tmp'...91.283333 seconds |Reading the file...67.116667 seconds | |IOZONE performance measurements: | 367586 bytes/second for writing the file | 499942 bytes/second for reading the file I wouldn't put this difference down to SCSI versus IDE, I would put most of it down to the poor IO performance of Ultrix. We recently had a DEC announcement of Ultrix 4.3 where they claim to have improved file IO by 100-300%, a figure I'm inclined to believe. I ran the Byte UNIX benchmarks on a DECsystem 8300 that we have here, its file IO performance was comparable to that of a Sun SPARCstation IPC's internal (slow) 207 MByte drive. File copy on both systems was approx 280 kBytes per second. In comparison a SUN 4/360 we have here turned in 1440 kBytes per second on file copy, this was using a 1.4 GByte SCSI disk on a slow SCSI II interface (5 Mbytes per second max). -- Phillip Fayers email: fayers@cardiff.ac.uk Sun admin/support/programming phone: 0222 874000 x 5282 (UK)