Confusion regarding vendor-unique feature pages

Henry Gabryjelski henrygab at
Thu Jul 22 10:21:03 PDT 2004

* From the T10 Reflector (t10 at, posted by:
* "Henry Gabryjelski" <henrygab at>

MMC3r10g on page 318 says "All Feature descriptors shall be a multiple
of four bytes."

Fuji5v150 on page 264 says "All Features shall be a multiple of four
bytes long."

Neither document seems to suggest that this requirement may be ignored
for vendor-unique feature pages, yet I have seen multiple drives
recently which are reporting vendor-unique pages that are not a multiple
of four bytes in length.

Are vendor-unique feature pages allowed to be any arbitrary length, or
are they supposed to also be constrained to multiples of four bytes in
length?  It would be good to have confirmation of my understanding.


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