Tony Battersby wrote:
Commands sent to ATAPI tape drives via the SCSI generic (sg) driver are limited in the amount of data that they can transfer by the max_sectors value. The max_sectors value is currently calculated according to the command set for disk drives, which doesn't apply to tape drives. The default max_sectors value of 256 limits ATAPI tape drive commands to 128 KB. This patch against 2.6.24-rc1 increases the max_sectors value for tape drives to 65535, which permits tape drive commands to transfer just under 32 MB. Tested with a SuperMicro PDSME motherboard, AHCI, and a Sony SDX-570V SATA tape drive. Note that some of the chipset drivers also set their own max_sectors value, which may override the value set in libata-core. I don't have any of these chipsets to test, so I didn't go messing with them. Also, ATAPI devices other than tape drives may benefit from similar changes, but I have only tape drives and disk drives to test. Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
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