Proposal to add a new modifier to SCSI Write commands. -Reply

Gerry Houlder Gerry_Houlder at
Mon Dec 2 11:33:18 PST 1996

* From the SCSI Reflector (scsi at, posted by:
* Gerry Houlder <Gerry_Houlder at>
Pat's message here is confusion over the original statement.
In the ".. so IT will not reassign the block" statement, IT refers
to the drive and not the initiator. This is a reference to the fact
that drives do not automatically reassign unrecoverable read
errors, only recoverable read errors.

Pat's confusion is understandable -- proper English rules suggest
that IT refers to subject of the first part of the sentence, which is
"the host". The original statement makes much more sense in
the context of the drive's reassignment rules (which are well
described in the standard) as opposed to the host's reassignment
rules (which aren't described in the standard).

>> The host gets an unrecovered read error,
>> so it will not reassign the block.  
>Am I correct to infer that the thinking here
>is that any host "should" try to overwrite a
>block before reassigning it?
>OK, I'll admit this rule - try overwrite
>before reassign - is elemental in removal
>media, since the unrecovered read may be due
>to an abused head in some other drive, or
>even transient transport damage, rather than
>indicative of media damage proper.
>But is this rule generally accepted?
>And have we yet written this rule into the
>dead forest that is a printed copy of the
>text authored by the SCSI committee?
>Pat LaVarre
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