On Wed, January 11, 2012 11:40, Nico Williams wrote:
> I don't find this terribly attractive, but maybe I'm just not looking
> at it the right way. Perhaps there is a killer enterprise feature for
> ECC here: stretching MTTDL in the face of a device failure in a mirror
> or raid-z configuration (but if failures are typically of whole drives
> rather than individual blocks, then this wouldn't help). But without
> a good answer for where to store the ECC for the largest blocks, I
> don't see this happening.
Not so much for blocks, but talking more with sectors, there's the T10
(SCSI) Data Integrity Field (DIF):
http://www.usenix.org/event/lsf07/tech/petersen.pdf
This is a controller-drive specification. For host-controller
communication, the Data Integrity Extensions (DIX) have been define:
http://oss.oracle.com/~mkp/docs/ols2008-petersen.pdf
It's a pity that the field is only eight bytes, as if it was larger, a
useful cryptographic [HCUG]MAC could be saved there by disk encryption
software. Perhaps with 4K-sector "Advanced Format" drives a similar field
will be defined that's larger.
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