Subject: Track buffering (was: DEV_B_SIZE)
To: Steve Byan <firstname.lastname@example.org>
From: Greg 'groggy' Lehey <grog@FreeBSD.org>
Date: 02/01/2003 12:57:16
On Friday, 31 January 2003 at 12:03:44 -0500, Steve Byan wrote:
> On Friday, January 31, 2003, at 11:50 AM, email@example.com wrote:
>> It was my impression that already many drives write entire tracks
>> as atomic units, at least we have had plenty of anecdotal evidence
>> to this effect ?
> I'm not aware of any SCSI or ATA disks which do this; certainly no
> Maxtor disk does. Count-key-data mainframe disks can be formatted to do
> so, but such disks probably don't run Unix. Caching in ATA disks might
> lead one to believe that the disk could corrupt an entire track, in the
> sense that a panic ( aka bluescreen) or a power-failure would cause all
> pending writes in its buffer to be lost, but even in ATA-land I don't
> believe a power failure would result in more than one disk block
> returning an uncorrectable read error.
A couple of years back I did some power fail testing on IBM IDE
drives. On one occasion I managed to blow out a whole range of
sectors (about 80), which I attributed to trashing a track buffer.
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