On 09/22/05 20:23, Douglas Gilbert wrote: > However an improved "sdparm -i" is not what you seem to be > asking for. Most of the above information is derived from > the response to the IDENTIFY [PACKET] DEVICE ATA command. > There seems to be two options for providing this: > 1) libata to implement ioctls like HDIO_GET_IDENTITY > 2) libata to implement SCSI ATA Translation [SAT] > facilities such as: > a) the ATA Information VPD page > b) SCSI ATA pass through commands > c) MODE SELECT SCSI command > > Option 1) is the simplest but it requires that the SAT layer > is on the host computer [as it is in the case of libata]. > Hopefully external USB and Firewire storage enclosures will > be enhanced to support the [draft] SAT standard and in > that case the SAT layer will be in the enclosure. SATA > disks [and S-ATAPI devices] in a SAS fabric may either > tunnel through the SAS fabric [via SAS Tunnelling Protocol > [STP]] or have a SAT layer in the fabric [typically in the > enclosure holding the disks]. There will be no SAT layer in a SAS fabric. STP is just that, a _tunneling_ protocol. Thus, either in Option 1, or Option 2 if you want to present the device to SCSI Core as a SCSI Device you need SAT somewhere below SCSI Core (on the host). In general, lower (hardware) layers want to do the _absolute_ minimum as far as their function is concerned. Thus, for example, you can expect an incomplete USB/IEEE1394 SAT layer on the device. > Only the STP route allows for option 1) . Option 2 as well: you'll just treat the device as SCSI and SAT will emulate as much as possible. Luben - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
