Greg Freemyer wrote:
Just so I know and before I try to find the right way to comment to the T13 and T10 committees: What is the negative of adding a ATA/SCSI command to allow the storage device to be interrogated to see what sectors/blocks/erase-units are in a mapped vs. unmapped state? For T13 (ATA), it would actually be a tri-state flag I gather: Mapped - last data written available unmapped - no data values assigned unmapped - deterministic data values Surely the storage device has to be keeping this data internally. Why not expose it?
.. That's a good approach. One problem on the drive end, is that they may not be maintain central lists of these. Rather, it might be stored as local flags in each affected sector. So any attempt to query "all" is probably not feasible, but it should be simple enough to "query one" sector at a time for that info. If one wants them all, the just loop over the entire device doing the "query one" for each sector. Another drawback to the "query all", is the size of data (the list) returned is unknown in advance. We generally don't have commands that work like that. Cheers -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
