Hi,
Alan Stern wrote:
>> Since most PL-3507 enclosures are probably user-upgradable and the most
>> recent
>> firmware doesn't have the off-by-one bug, it might be better to not
>> include
>> that UNUSUAL_DEV entry. Otherwise, e.g. using dd to create an image file
>> of the
>> disk omits the last sector.
>
> How is the kernel supposed to tell whether or not an enclosure is
> running the latest firmware? We don't want drives that haven't been
> updated yet to suddenly stop working right.
That's a good question. There may not be anything in the lsusb output (see
below) to indicate the firmware version. It is definitely possible to
determine the version though; the Prolific flashing program does that. I
haven't looked at its code to see exactly how it talks to the enclosure.
There is a changelog In the firmware archive on the Prolific web site but
none of the entries explicitly states when the off-by-one error was fixed.
What is the typical failure mode if a device with off-by-one capacity bug
is connected? I'm assuming the kernel tries to read (what it thinks is)
the last sector, which fails. Does the kernel then refuse to access the
device at all? Or is the issue that the device itself crashes/hangs on
receiving a READ command for a too-large LBA?
At least with my enclosure (with the most recent firmware), attempting a
read beyond the end of the disk returns an error as it should, and the
enclosure doesn't appear to lock up on receiving that command. Of course
the behaviour of earlier firmware versions may differ.
The disk in the enclosure has 39102336 512-byte sectors, so the last LBA
is 39102335.
Try reading the last block:
# sg_read blk_sgio=1 bpt=1 bs=512 cdbsz=10 count=1 if=/dev/sg2
skip=39102335 verbose=3
Opened /dev/sg2 for SG_IO with flags=0x2
SG_GET_RESERVED_SIZE yields: 32768
read cdb: 28 00 02 54 a7 7f 00 00 01 00
duration=0 ms
1+0 records in, SCSI READ commands issued: 1
Try reading the block *after* the last one, which should fail:
# sg_read blk_sgio=1 bpt=1 bs=512 cdbsz=10 count=1 if=/dev/sg2
skip=39102336 verbose=3
Opened /dev/sg2 for SG_IO with flags=0x2
SG_GET_RESERVED_SIZE yields: 32768
read cdb: 28 00 02 54 a7 80 00 00 01 00
duration=144 ms
reading: Host_status=0x07 [DID_ERROR]
plus...: Driver_status=0x08 [DRIVER_SENSE, SUGGEST_OK]
Fixed format, current; Sense key: Hardware Error
Additional sense: No additional sense information
Raw sense data (in hex):
70 00 04 00 00 00 00 0a 00 00 00 00 00 00 00 00
00 00
sg_read: SCSI READ medium/hardware error
Some error occurred, remaining block count=1
0+0 records in
> Can you provide the output from "lsusb -v" for the new firmware?
$ sudo lsusb -v -d 067b:3507
Bus 002 Device 004: ID 067b:3507 Prolific Technology, Inc. PL3507 ATAPI6
Bridge
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x067b Prolific Technology, Inc.
idProduct 0x3507 PL3507 ATAPI6 Bridge
bcdDevice 0.01
iManufacturer 1 Prolific Technology Inc.
iProduct 2 ATAPI-6 Bridge Controller
iSerial 3 1
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 32
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 2mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk (Zip)
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0001
Self Powered
-- Mark
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