Re: Data authentication for geli(8) committed to HEAD.

From: Wilko Bulte <wb_at_freebie.xs4all.nl>
Date: Fri, 9 Jun 2006 08:53:11 +0200
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_at_FreeBSD.org
Received on Fri Jun 09 2006 - 04:53:26 UTC

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