Date: Mon, 26 Nov 2001 17:20:51 -0600 From: Bob Willcox <bob@immure.com> To: "Brian T.Schellenberger" <bts@babbleon.org> Cc: "Patrick O'Reilly" <patrick@mip.co.za>, Nils Holland <nils@tisys.org>, FreeBSD Question List <freebsd-questions@FreeBSD.ORG> Subject: Re: Softupdates Message-ID: <20011126172050.A63285@luke.immure.com> In-Reply-To: <01112609195201.00903@i8k.babbleon.org>; from bts@babbleon.org on Mon, Nov 26, 2001 at 09:19:52AM -0500 References: <NDBBIMKICMDGDMNOOCAIOENHDPAA.patrick@mip.co.za> <01112609195201.00903@i8k.babbleon.org>
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On Mon, Nov 26, 2001 at 09:19:52AM -0500, Brian T.Schellenberger wrote: [snip] > Also, you most definately should turn off write-caching if you turn on > softupdates. In fact, you should do this anyway: softupdates are really > rather safe, but write caching is quite dangerous, and doubly so with > softupdates enabled. > > To do this, set > > hw.ata.wc=0 > > in your /boot/loader.conf (assuming IDE devices). In my experience, the current crop of ATA disks (I mostly have IBM) write _much_ slower with write caching disabled (on the order of a magnitude or more). Consequently, I find disabling it most undesirable. Instead, I suggest that you invest in a UPS so that your chance of suddenly dropping power to the disk is acceptably low...this is what I have done. (I don't think your average system crash where power stays up should be a problem since the disk would then have time to flush its cache.) BTW, the performance on SCSI disks doesn't seem to be nearly as adversly affected by disabling write caching (perhaps due to their higher-level command interface, esp. command tag queuing). Any disk experts out there should correct me on this if I'm off base (but this has been my experience). [snip] Bob -- Bob Willcox Boucher's Observation: bob@vieo.com He who blows his own horn always plays the music Austin, TX several octaves higher than originally written. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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