[T10] WRITE SAME and 0 LBA counts

Sitsofe Wheeler sitsofe at gmail.com
Tue May 17 22:36:51 PDT 2016


According to SBC specs if the target's WSNZ bit is 0 and the WRITES
SAME's NUMBER OF LOGICAL BLOCKS is set to 0 then the LBA from the
LOGICAL BLOCK ADDRESS field to the last logical block on the medium
should be written. However, it also says if the number of logical
blocks specified to be written exceeds the MAXIMUM WRITE SAME LENGTH a
CHECK CONDITION/ILLEGAL REQUEST/INVALID FIELD IN CDB should be raised.

When the spec says "number of logical blocks specified to be [...]
written" is this only in reference to the NUMBER OF LOGICAL BLOCKS
passed in rather than the computed number of blocks to be written or
is there a choice over which is used (i.e. the target can pick whether
it errors or not if the computed blocks exceed the MAXIMUM WRITE SAME
LENGTH)?

For example, if I have an *SBC-3* 1GByte target with a WSNZ of 0 and a
MAXIMUM WRITE SAME LENGTH of 131072 blocks (64Mbytes with a sector
size of 512), then I issue a WRITE SAME with NUMBER OF LOGICAL BLOCKS
of 0 and a LOGICAL BLOCK ADDRESS of 0 is it legal for the SBC-3 target
to produce an error because the computed number of blocks to be
written will be greater than 131072?

-- 
Sitsofe | http://sucs.org/~sits/


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