lkml.org 
[lkml]   [2001]   [Jul]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] 64 bit scsi read/write
On Sun, Jul 15, 2001 at 09:16:09AM -0400, Ken Hirsch wrote:

The first technique is not sufficient with modern disk
controllers, which may reorder sector writes within a block. A
checksum, especially a robust CRC32, is sufficient, but rather
expensive.

So you write the number to the start and end of each sector, or, you
only assume sector-wide 'block-sizes' for integrity.

A 32-bit CRC is plenty cheap enough on modern CPUs and especially
considering how often you need to calculate it.

Mohan has a clever technique that is computationally trivial and
only uses one bit per sector:
http://www.almaden.ibm.com/u/mohan/ICDE95.pdf

Unfortunately, it's also patented:
http://www.delphion.com/details?pn=US05418940__

Perhaps IBM will clarify their position with respect to free
software and patents in the upcoming conference.

Wow... pretty neat, but fortunately not necessary.



--cw
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:57    [W:0.103 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site