On 2020/03/26 16:28, Christoph Hellwig wrote: > On Thu, Mar 26, 2020 at 01:30:12PM +0900, Damien Le Moal wrote: >> Similarly to the zone write pointer reset operation (REQ_OP_ZONE_RESET), >> the zone open, close and finish operations can operate on all zones of a >> ZBC or ZAC SMR disk by setting the all bit of the command. Compared to a >> loop issuing a request for every zone of the device, the device based >> processing of an all zone operation is several orders of magnitude >> faster. > > What is the point? None of these actually seem like remotely useful > operations. Why would I ever want to open or finish all zones? > Open & Close all zones are indeed not super useful, at least on SMR drives. But finishing all zones does have some benefit, namely the ability to quickly change all incompletely written zones into "read-only" full zones. For drives with low zone resources (open or active zones), this can be useful to recover zone resources. Again, not so much on SMR drives, but this could come in handy for ZNS drives with low zone resources (max open zones etc). -- Damien Le Moal Western Digital Research
