Comments on T10 proposal 05-101r1

Gerry.Houlder at Gerry.Houlder at
Tue May 17 13:19:53 PDT 2005

* From the T10 Reflector (t10 at, posted by:
* Gerry.Houlder at
This proposal adds wording that states "A LOGICAL BLOCK APPLICATION TAG
field set to FFFFh disables checking of all protection information for the
logical block when reading from the medium."

I don't believe this restriction is a good idea. This disabling of all
checking should also occur for writes as well.

Consider design of target hardware to implement this function. The hardware
needs to be designed so that an Application Tag value of FFFFh overrides
any checking that would otherwise be permitted by the RDPROTECT field in
the CDB. Now imagine that the same hardware will be used for checking data
|from a WRITE command. Is it reasonable that the target should redesign the
same hardware so that  the WRPROTECT field overrides the Application Tag
value of FFFFh? We don't think so.

If there is another reason (other than just making the wording more
specific) I'd like to hear it. Otherwise I would like to see this change
withdrawn or I make a new proposal that changes the wording to "either
writing or reading".

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