pCRC interval for Duoble Transition, non-IU transfers

Mark Emmer marke at snobol4.com
Mon Aug 11 14:07:48 PDT 2003

* From the T10 Reflector (t10 at t10.org), posted by:
* "Mark Emmer" <marke at SNOBOL4.com>
Hello all,

I'm looking for guidance on selecting pCRC intervals (i.e., Data Group lengths)
for non-packetized, wide, Fast-10 through Fast-80 Double Transition data
transfers.  (IU=0, DT=1 in PPR message).

Searching SPI-4, there does not appear to be any mode page setting that controls
this value, which I guess makes sense since the interval is completely under the
control of the target for both DT Data In and DT Data Out.

Given the dilution of pCRC strength with increasing Data Group length, one would
not want to be doing a megabyte transfer and relying solely on a single,
end-of-transfer pCRC for data integrity.

Are there any commonly accepted values (2 KB, 4 KB, etc.) for partitioning a
long transfer into smaller data groups?

Thank you,

Mark Emmer

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