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On Mon, 17 Dec 2001 12:47:08 -0700, Pat LaVarre wrote: >An x0A/2A/AA Write block command that fails renders all the >content of the blocks it addresses indeterminate? Maybe commonly >only the blocks before the bad block changed, but only a BadHost >assumes that limited effect? ATAPI might look like SCSI but it is SCSI using the ATA/ATAPI interface as the transport. In ATA/ATAPI a host SHALL assume that any data read from a device during a read command that ends with an error is "bad data". The host SHALL not use any of the data received from the device. So even if the host is reading 200 sectors and it would appear that the first 100 had no error the host is not allowed to assume that. The host SHALL assume that ALL sector data received from the device (even those first 100 in this case) are not valid data. >A device can avoid using intermediate data only by buffering all >the data of the command. For a write command that ends with an error the host SHALL assume that NONE of the data that was transferred to the device was used in any way by the device. Yes, the device may have written some of the data to the media without error but the host SHALL NOT assume this. Remember that for write commands, ATA/ATAPI does not require the device to write the data in the same time order as it was received from the host. This true even when write caching is off. The device may write the data "out of order" so that a 200 sector write might write the middle sectors to the media before writing the first sectors. *** Hale Landis *** [EMAIL PROTECTED] *** *** Niwot, CO USA *** www.ata-atapi.com *** Subscribe/Unsubscribe instructions can be found at www.t13.org.
