Date: Thu, 13 Jun 1996 22:29:15 +0200 From: "Julian H. Stacey" <jhs@freebsd.org> To: "Hr.Ladavac" <lada@ws2301.gud.siemens.co.at> Cc: scsi@freebsd.org, fabio@cesar.unicamp.br, fty@mcnc.org, gcrutchr@nightflight.com, j@uriah.heep.sax.de, jc@irbs.com, julian@freebsd.org, kuku@gilberto.physik.rwth-aachen.de, lehey.pad@sni.de, mrm@sceard.com, nikm@ixa.net, tomppa@fidata.fi, wilko@yedi.iaf.nl, scott@relay.forest.com Subject: Re: 8 * 0xFF bytes at intermittent multiples of 0x1000 Message-ID: <199606132029.WAA28493@vector.jhs.no_domain> In-Reply-To: Your message of "Thu, 13 Jun 1996 09:48:17 %2B0200." <199606130748.AA221852097@ws2301.gud.siemens.co.at>
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Hi, Reference: > From: "Hr.Ladavac" <lada@ws2301.gud.siemens.co.at> > In his e-mail Julian H. Stacey wrote: > > To scsi@freebsd.org > > Cc Adaptec 1542A SCSI Adapter People, Julian Elischer. > > > > > > I connected sd1 to my 1542A and here are results: > > > > > > > > 1. No problems if testblock is only one that generates disk activity. > > > > 2. I launched couple find processes to sd0 and at same time I > > > > run testblock. Testblock failed only 1/10 of test runs. > > > > 3. I copied files with cp to sd1 when running testblock on > > > > sd1. Testblock failed on every time. > > > > > > > > Tomppa > > It need not be FreeBSD specific. I had a very similar problem a couple of > years ago with a 1542CF and Seagate 540 MB disk *WITH LINUX* Pretty scary if we're still in the same dumb scenario we were in 20 years ago, back then it was `Unix assumes perfect hardware' If we're still doing no checks on what the hard disks deliver, it's time to shiver with fear ;-) (though I realise implications WRT FFS definition & portability if we were to add checks, tricky that.) > The problems went away when I've thrown out the IDE disk on which I had > the /usr partition (i.e., it was always in use.) I've used dd < /dev/zero > and my own simple C program for testing. I have no IDE :-) My program started years on a 4.3 with no /dev/zero, & now does a rolling bytes offset within blocks, to detect skipped blocks. > Errors appeared, but there was no regularity whatsoever. Mine is regular 8 * 0xFF every few 0x1000 > However, in my > case the errors were simply inverted bits, 90% of the time 1 inverted bit, > very seldom 2 bits. Sounds like no commonality. > Since it never occured afterwards, I've dismissed it as the bus-noise > generated by an ancient IDE device. Mine is a short internal ribbon, good firm contacts, properly terminated. > Needless to say, the same machine, other machines with the very same > Adaptec/Seagate combo behaved okay, even in presence of other SCSI devices. Well at least one other person is seeing exactly what I'm seeing he posted his log. Julian -- Julian H. Stacey jhs@freebsd.org http://www.freebsd.org/~jhs/
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