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Path: sserve!newshost.anu.edu.au!munnari.oz.au!spool.mu.edu!howland.reston.ans.net!gatech!swrinde!pipex!sunic!trane.uninett.no!eunet.no!nuug!EU.net!Germany.EU.net!news From: bs@Germany.EU.net (Bernard Steiner) Newsgroups: comp.os.386bsd.questions Subject: scsi fs tuning Date: 7 Jul 1994 16:34:26 +0200 Organization: EUnet Deutschland GmbH, Dortmund, Germany Lines: 26 Distribution: world Message-ID: <2vh3pi$lq2@Germany.EU.net> NNTP-Posting-Host: qwerty.germany.eu.net Hi there, I seem to have a slight problem with tuning my scsi disk filesystem: i/o to the raw device reads about 2MB/sec with 64k blocks (10 Meg to /dev/null), but reading 10 Meg from a file on a 512/4096 filesystem on the disk gives about the same silly results as reading 4k blocks off the raw device. Well, dumpfs told me the rotational delay was assumed to be 4 ms. After buildig a new filesystem with rot-delay set to 0, I can now get 1MB/sec on continuous read from a 10 Meg file in a 512/4096 filesystem. Instead of fiddling with obscure parameters - is there any program that tells me what to do about these parameters (like headswitch tim, track-to-track seek time, interleave, sector skew, etc.) ? Or is there a recommended step-by-step refinement towards an optimal set of parameters ? And how do I go about disabling the cache on the disk without using a soldering iron ? Thanks, Bernard