Date: Wed, 14 Oct 1998 09:18:56 -0600 From: Nate Williams <nate@mt.sri.com> To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: Nate Williams <nate@mt.sri.com>, Terry Lambert <tlambert@primenet.com>, Don.Lewis@tsc.tdk.com, julian@whistle.com, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: filesystem safety and SCSI disk write caching Message-ID: <199810141518.JAA05051@mt.sri.com> In-Reply-To: <199810141509.JAA07471@pluto.plutotech.com> References: <199810141501.JAA04936@mt.sri.com> <199810141509.JAA07471@pluto.plutotech.com>
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> >Bottom line is that by default FreeBSD w/SoftUpdates is more *unstable* > >now with CAM than it was w/out CAM for 99% of the users. > > Please don't add any more FUD to this thread than there is already. > > CAM has nothing to do with this issue. Neither the old SCSI code nor the > new CAM code has ever modified the caching behavior of the devices attached > on the bus. Previous email imply that it has the ability to disable/enable write-caching the addition of quirks entries for certain devices. > My position on this is that we should *never* modify device > mode parameters unless instructed to do so by the end user. If the user > community insists that we add a warning about the cache being enabled, now, > after years of silently ignoring the effects of the cache on filesystem > integrity, so be it. My opinion is that if this was a problem in practice, > we'd have heard about it by now from our user community. Up till this point, we never had any FS code that attempted to deal with 'crashing' robustly. I for one knew that if my machine crashed, an fsck was expected and it was going to repair my disk. This is no longer the case with SoftUpdates, so what was previously attributed to 'the crash' can now be more fine-tuned to 'write caching screwed up' or 'I have a bad power supply which breaks my drive when I hit the reset button' or even simply 'when I lose power, write-caching spams my disk'. With better information more informed decisions can be made. (Now is that a redundant statement or what? *grin*) Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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