Date: Fri, 9 Jun 2006 08:53:11 +0200 From: Wilko Bulte <wb@freebie.xs4all.nl> To: "Daniel O'Connor" <doconnor@gsoft.com.au> Cc: freebsd-current@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: Data authentication for geli(8) committed to HEAD. Message-ID: <20060609065311.GB4251@freebie.xs4all.nl> In-Reply-To: <200606091215.41787.doconnor@gsoft.com.au> References: <20060608132048.GD86198@garage.freebsd.pl> <20060608174113.GC1075@roadrunner.q.local> <200606091215.41787.doconnor@gsoft.com.au>
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On Fri, Jun 09, 2006 at 12:15:33PM +0930, Daniel O'Connor wrote.. > On Friday 09 June 2006 03:11, Ulrich Spoerlein wrote: > > I have an external HDD that I initially attached via Firewire, but I've > > since switched to USB, as our firewire subsystem is less than rock > > Interesting. I find the reverse :) > Then again I started using Firewire in 4.x where USB2.0 didn't exist and the > USB 1 code was kind of dodgy. > > > The question really is, are 512 byte disk writes considered to be some > > kind of "atomic" as it is the smallest disk block size? What does the > > ATA subsystem do with writes of 4096? Are they completed atomically too, > > or not? > > I think that in reality with a modern high capacity disk you don't get atomic > writes at all because they all re-write whole tracks. > > Yes this violates the assumption soft updates makes, I believe the only way > around it is to buy SCSI drives (not because they're SCSI per se, but because > they're smaller capacity so they don't do this) Don't tell my 300GB SCSI disks (at work) that they are 'small'. -- Wilko Bulte wilko@FreeBSD.org
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