On Mon, Jul 09, 2012 at 06:24:15PM -0400, Robert Trace wrote: > On 07/09/2012 04:45 PM, Darrick J. Wong wrote: > > > > I suspect that /sys/devices/<bunch of sas topology here>/manage_start_stop = 0 > > for the SATA devices hanging off the SAS controller. > > Yep, looks like you're right. For my system: > > # cat /sys/block/sd?/device/scsi_disk/*/manage_start_stop > 1 > 1 > 1 > 1 > 1 > 0 > 0 > 0 > 0 > 0 > 0 > 0 > 0 > > Those first 5 disks are SATA disks on SATA controllers. The last 8 > disks are SATA disks on the SAS controller. > > > Setting that sysfs > > attribute to 1 is supposed to enable the SCSI layer to send TUR when it sees > > "LU not ready", as well as spin down the drives at suspend/poweroff time. > > Setting it to 1 doesn't seem to have made any difference, however. > > # cat /sys/block/sdm/device/scsi_disk/14\:0\:7\:0/manage_start_stop > 0 > # echo 1 > /sys/block/sdm/device/scsi_disk/14\:0\:7\:/manage_start_stop > # cat /sys/block/sdm/device/scsi_disk/14\:0\:7\:0/manage_start_stop > 1 > # hdparm -y /dev/sdm > > /dev/sdm: > issuing standby command > # hdparm -C /dev/sdm > > /dev/sdm: > drive state is: standby > # dd if=/dev/sdm of=/dev/null bs=512 count=1 > dd: reading `/dev/sdm': Input/output error > 0+0 records in > 0+0 records out > 0 bytes (0 B) copied, 0.00117802 s, 0.0 kB/s > > ... and on the scsi logging side, I see the read(10) to the disk which > immediately returns "Not Ready" and the I/O failure bubbles up the > chain. And afterwards, the disk is still asleep. > > # hdparm -C /dev/sdm > > /dev/sdm: > drive state is: standby > > Also, TURs don't appear to actually wake the disk up (should they?). > The only thing I've found that'll wake the disk up is an explicit START > UNIT command. Sorry, I misspoke, manage_start_stop=1 sends START UNIT, not TUR. Also, it only manages spindown/up at suspend/resume time, hence the behavior you see. The relevant source code is sd_start_stop_device() in drivers/scsi/sd.c. --D > > -- Rob > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
