>>>>> "Heinz" == heinzm <heinzm@xxxxxxxxxx> writes: Heinz, > +Discard Support > +--------------- > +The implementation of discard support amoung hardware vendors varies. When > +a block is discarded, some storage devices will return zeros when it is > +read. These devices set the 'discard_zeros_data' attribute. Other devices > +will return random data. Confusingly, some devices will set > +'discard_zeros_data', but will still not always return zeros when > +discarded blocks are read! This used to be correct but that's no longer the case. We only set discard_zeroes_data when we have hard guarantees. We no longer exclusively rely on what the device reports. discard_zeroes_data is only set if the device reports LBPME/LBPRZ and uses WRITE SAME 10 or 16 (SCSI) or if it reports DRAT/RZAT and is explicitly whitelisted (ATA). -- Martin K. Petersen Oracle Linux Engineering -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
