On Wed, Nov 7, 2012 at 12:14 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 7 Nov 2012, Jason J. Herne wrote:
>
>> > Most likely that's the answer. Of course, for a device to recognize
>> > READ(16) but not READ(10) is a violation of the SCSI spec.
>> >
>> > I don't know what criterion Windows uses. Maybe it uses READ(16)
>> > whenever the total capacity is >= 2^32 blocks.
>>
>> I've not had enough time to properly find where/how to fix/hack this
>> into the code.
>
> It won't be simple. The current algorithm has been working for a long
> time, so people won't want to change it.
>
>> I'll keep looking at it. Does there happen to be any "quirks" that might help?
>
> No.
>
>> Also, i assume the place to look is drivers/usb/storage?
>
> No. The decision about which command to use is made in
> drivers/scsi/sd.c, in sd_prep_fn(). Look at the lines starting with
>
> } else if (block > 0xffffffff) {
>
> (line 891 in my copy of the file).
>
>> Is anything in drivers/scsi related?
>> Forgive my ignorance, my kernel development experience is primarily in
>> the realm of kvm.
>> Any tips you could provide would be most appreciated.
>
> What happens if you put a smaller drive (under 2 TB) in that enclosure?
> Does it then work with READ(10) or does it still require READ(16)?
>
I just put a Seagate ST315003 1.5 GB Sata drive in this enclosure and captured
USB with Wireshark on Linux. The USB trace shows READ(10) is use, and the
drive appears to work.
# dmesg
[128481.865196] usb 1-1.2: new high-speed USB device number 5 using ehci_hcd
[128482.072178] scsi13 : usb-storage 1-1.2:1.0
[128492.244106] scsi 13:0:0:0: Direct-Access ST315003 41AS
CC1H PQ: 0 ANSI: 0
[128492.245340] sd 13:0:0:0: Attached scsi generic sg3 type 0
[128492.245921] sd 13:0:0:0: [sdc] 2930277168 512-byte logical blocks:
(1.50 TB/1.36 TiB)
[128492.246767] sd 13:0:0:0: [sdc] Write Protect is off
[128492.246774] sd 13:0:0:0: [sdc] Mode Sense: 23 00 00 00
[128492.248526] sd 13:0:0:0: [sdc] No Caching mode page present
[128492.248533] sd 13:0:0:0: [sdc] Assuming drive cache: write through
[128492.251033] sd 13:0:0:0: [sdc] No Caching mode page present
[128492.251039] sd 13:0:0:0: [sdc] Assuming drive cache: write through
[128492.281814] sdc: sdc1 sdc2
[128492.285558] sd 13:0:0:0: [sdc] No Caching mode page present
[128492.285563] sd 13:0:0:0: [sdc] Assuming drive cache: write through
[128492.285566] sd 13:0:0:0: [sdc] Attached SCSI disk
[128493.584668] kjournald starting. Commit interval 5 seconds
[128493.585548] EXT3-fs (sdc1): warning: maximal mount count reached,
running e2fsck is recommended
[128493.587108] EXT3-fs (sdc1): using internal journal
[128493.587115] EXT3-fs (sdc1): mounted filesystem with ordered data mode
--
- Jason J. Herne (hernejj@xxxxxxxxx)
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