Discussion about 11-376 -- add extension for defect descriptors

Gerry Houlder gerry.houlder at seagate.com
Thu Sep 22 07:27:34 PDT 2011


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1109223_f.htm">HTML-formatted message</a>

OK, I am convinced the direction discussed at the CAP meeting is still the
right direction ..
On Tue, Sep 20, 2011 at 7:59 PM, Jon Haswell - SISA <
jon.haswell at sisa.samsung.com> wrote:
> Speaking as an SSD supplier …****
>
> ** **
>
> We do not actually use the vendor unique field but map our defects into the
> existing formats such as Byte from Index. We do this at our customers
> request as their systems expect to be able to read back or send defect
lists
> in these formats across HDDs and SSDs.****
>
> ** **
>
> Our mapping into a format such as Bytes From Index is not truly meaningful
> if you try and interpret it, but we and our customers effectively just use
> it as an opaque container with other higher level software that is able to
> interpret it used during failure analysis or the like.****
>
> ** **
>
> Personally I don’t see a need/desire for new formats for SSDs. I believe
> every SSD will effectively use a proprietary format for reporting defects
> and it would be very difficult and of little value to try and standardize
> it.****
>
> ** **
>
> Thanks****
>
> ** **
>
> Jon Haswell****
>
> Dir SSD Development****
>
> Office  408 544 5869****
>
> Cell	   408 472 2495****
>
> ** **
>
> *From:* owner-t10 at t10.org [mailto:owner-t10 at t10.org] *On Behalf Of *Gerry
> Houlder
> *Sent:* Tuesday, September 20, 2011 2:41 PM
>
> *To:* T10 Reflector
> *Subject:* Discussion about 11-376 -- add extension for defect descriptors
> ****
>
> ** **
>
> Hi everyone,****
>
> ** **
>
> During discussion of 11-376r0 at the September CAP meeting, I was given
> direction to use two new address descriptor values for the new Bytes From
> Index and Cylinder Head Physical Block formats. If I do this, this will
> consume two of the three reserved codes.****
>
> ** **
>
> Before I do this, I'd like to point out that the currently defined address
> formats are not very applicable to Solid State Drives. I suspect these
> drives use the vendor specific option today, if they support any of the
> options at all. Is there any thought that there needs to be standard defect
> descriptor formats that are designed for SSD use? If so, then it might *
> not* be a good idea to consume two of the three remaining defect list
> formats for HDD use.****
>
> ** **
>
> This direction was instigated by the head field not being able to give up
> one of its bits for the MADS function. If the bit was carved from the most
> significant bit of the four byte BYTES FROM INDEX or SECTOR NUMBER fields,
> would this make it more acceptable to extend the current address descriptor
> formats instead of creating new ones?****
>
> ** **
>
> I'd like to see more discussion on whether new address formats are needed
> for SSD or other new technology products before committing to using up two
> more address descriptor formats. Note that we are constrained by the 3 bit
> field in the FORMAT command to a maximum of 8 address formats. However, I
> suppose this could be expanded if SBC-3 reclaimed the two obsolete bytes in
> the FORMAT CDB, the 111b code could be a trigger to get the actual address
> descriptor format from of of these bytes ...****
>



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