parity handling

PAT LaVARRE (PAT LAVARRE) LAVARRE at iomega.com
Tue Feb 6 06:05:32 PST 1996


* From the SCSI Reflector, posted by:
* PAT LaVARRE (PAT LAVARRE) <LAVARRE at IOMEGA.COM>
*
Quoting <Gerry_Houlder at notes.seagate.com>:

> Writing a known bad block to media goes
> against all the rules of data integrity.
> ...
> Initiator recovery routines are supposed
> to assume that the bad block and all
> blocks after the bad block have not been
> written to media.

Eh?

I of course agree that a first-rate target
implementation (: like ours :) would support
such an assumption when the failure in
question is a data out parity error ...

... but I thought that technically
initiators were required to assume CORRUPT -
possibly written, possibly not, possibly
scrambled beyond ECC recovery - every LBA
addressed by the transfer?

For example, if the host sees a check
condition on a write of x100 blocks to LBA
x123, blocks x123 .. x222 may be corrupt?

Exception:  If the info field of the sense
data is flagged valid, the LBAs preceding
the info LBA were written OK.

No?

Thanks in advance.   Pat LaVarre






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