On 2018-03-15 10:47 AM, Kashyap Chamarthy wrote:
On Wed, Mar 14, 2018 at 11:43:55PM -0400, Martin K. Petersen wrote:
Kashyap,
Hi Martin,
Sorry, I didn't give you complete information — with the previous
`dmesg` output, I actually attached the SSD (Samsung T5) via regular USB
"A Cable".
Now, I re-attached the SSD via the "Thunderbolt" port on my other laptop
(Lenovo T470s), it _does_ show "UAS". Refer the arrow below:
Do you get different sg_readcap -l output when accessing it in UAS mode?
I.e. is lbpme=1?
Afraid, no :-( I was excited for a brief moment, but it's the same as
earlier. The result with the SSD via 'Thunderbolt':
$> sudo sg_readcap -l /dev/sdc
Read Capacity results:
Protection: prot_en=0, p_type=0, p_i_exponent=0
Logical block provisioning: lbpme=0, lbprz=0
Last logical block address=976773167 (0x3a38602f), Number of logical blocks=976773168
Logical block length=512 bytes
Logical blocks per physical block exponent=0
Lowest aligned logical block address=0
Hence:
Device size: 500107862016 bytes, 476940.0 MiB, 500.11 GB
/me naively wonders if it has anything to do with accessing it via
Linux.
You can also run 'sg_readcap -l' on a Windows machine to test your theory.
Do 'sg_scan.exe' first to see where (and if) the 'physical disk' is, then
you would do something like:
sg_readcap -l pd2
There is no IOS port of sg3_utils.
I am not aware of any SCSI command *** (and haven't seen any ATA or NVMe
commands) that tell a storage device something like: "BTW I'm a Linux
machine running Ubuntu 17.10 on xxxx hardware".
It is possible that a storage device might recognize an OS by the pattern
of commands it sends, especially in the device discovery mode.
So basically your suggestion is a long shot. There might be a "secret"
setting in a vendor specific command that another OS is aware of.
For example, according to the 'net this command:
sg_raw /dev/sr0 EA 00 00 00 00 00 01
allows owners of Apple USB Superdrives to use them on other OSes.
Doug Gilbert
*** there are transport_ids used by PERSISTENT RESERVATION commands to
differentiate one machine from another. But they convey about as
much information as a random number does. Also that applies to a
multi-initiator, single target model which isn't the case when we
are talking about USB/Thunderbolt attachment.
