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Curtis Stevens wrote:
This message is from the T13 list server.
I agree...
I think we are getting to the purpose of the CDB transport mechanism at this point. My current vision is manufacturing and maintenance. This would mean that SCSI would be the normal mode of operation for reading and writing the media. However, in the case of a bridged (P/S)ATA device (USB, 1394, SAS, etc) you may want to tech support the device by issuing a SMART command. Using CDB pass-through, I think this can be done using existing standard driver pass-throughs. It would also allow device failure diagnosis without opening the box and removing the ATA device. Our major use will be for vendor specific commands...
At this point, I do not really see this being used in a performance environment. So, the devices will already have to deal with the SCSI
I agree, and further I think SMART/vendor-reserved/maintenance commands will be 99% of the usage of an ATA passthru command.
The fast path will simply be standard SCSI read/write commands, translated to ATA commands in the obvious way.
presentation issue. The one case I can see is if there are many drives presented as one device by the SCSI-ATA bridge. Then there would need to be a mechanism for addressing the individual ATA drives. I think in this environment (which is starting to look like a RAID), there is a bigger problem to solve.
In fact, there are already RAID products on the market that roll their own ATA passthru for precisely the reasons stated. Typically these products provide a product-specific method of addressing the individual drives outside the scope of the ATA command (CDB) being sent to the individual device.
Jeff
