Hi all
I am discussing about an issue I get with my Orico USBtoSATA 5 bays enclosure
The issue is that every 5 minutes the BTRFS perform a revalidate
action that will fill the dmesg with this log:
[ 98.917660] sd 0:0:0:1: [sdb] Very big device. Trying to use READ
CAPACITY(16).
[ 99.057592] sd 0:0:0:0: [sda] Very big device. Trying to use READ
CAPACITY(16).
[ 99.304848] sd 0:0:0:2: [sdc] Very big device. Trying to use READ
CAPACITY(16).
[ 99.465374] sd 0:0:0:3: [sdd] Very big device. Trying to use READ
CAPACITY(16).
[ 99.669241] sd 0:0:0:4: [sde] Very big device. Trying to use READ
CAPACITY(16).
After some investigation I think I have found out the reason
The sd_read_capacity in scsi layer check if read_capacity_10 or
read_capacity_16 should be used
It does it based on what this function return:
static int sd_try_rc16_first(struct scsi_device *sdp)
{
if (sdp->host->max_cmd_len < 16)
return 0;
if (sdp->try_rc_10_first)
return 0;
if (sdp->scsi_level > SCSI_SPC_2)
return 1;
if (scsi_device_protection(sdp))
return 1;
return 0;
}
the problem is that in the usb to scsi glue layer, the try_rc_10_first
is picked like this:
/*
* Many devices do not respond properly to READ_CAPACITY_16.
* Tell the SCSI layer to try READ_CAPACITY_10 first.
* However some USB 3.0 drive enclosures return capacity
* modulo 2TB. Those must use READ_CAPACITY_16
*/
if (!(us->fflags & US_FL_NEEDS_CAP16))
sdev->try_rc_10_first = 1;
Are we sure this is the correct option? I mean to me the default
should be to go for rc_10 if there is a specific request in the
unusual devices, rather then if we dont' need cap16 we go for it,
like:
if ((us->fflags & US_FL_NEEDS_CAP10))
sdev->try_rc_10_first = 1;
What you think about?
Bye
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