Ewan, > Some devices do not support a WRITE SAME / WRITE SAME(16) with the > UNMAP bit set up to the length specified in the MAXIMUM WRITE SAME > LENGTH field in the block limits VPD page (or, the field is zero, > indicating there is no limit). Limit the length by the MAXIMUM UNMAP > LBA COUNT value. Otherwise the command might be rejected.
>From SBC4: "A MAXIMUM UNMAP LBA COUNT field set to a non-zero value indicates the maximum number of LBAs that may be unmapped by an UNMAP command" Note that it explicitly states "UNMAP command" and not "unmap operation". "A MAXIMUM WRITE SAME LENGTH field set to a non-zero value indicates the maximum number of contiguous logical blocks that the device server allows to be unmapped or written in a single WRITE SAME command." It says "unmapped or written" and "WRITE SAME command". The spec is crystal clear. The device needs to be fixed. We can blacklist older firmware revs. -- Martin K. Petersen Oracle Linux Engineering
