On Thu, Mar 15, 2018 at 08:45:05AM -0400, Martin K. Petersen wrote:
> 
> Kashyap,
> 
> > /me naively wonders if it has anything to do with accessing it via
> > Linux.
> 
> I'm guessing that the drive doesn't actually support SCSI UNMAP. I have
> a T3 that reports all the right things in the bl/lbpv VPD pages but also
> has lbpme set to 0.
> 
> Interestingly enough, my T3 does appear to be a regular SATA drive
> behind a USB bridge. 

I see.  So I ran `hdparm` on my SSD (still attached via the
'Thunderbolt' port), and it does show TRIM support:

    $> hdparm -I /dev/sdc | grep TRIM
               *    Data Set Management TRIM supported (limit 8 blocks)

(Full output attached to this e-mail as a text file.)

> Have you tried to issue a DSM TRIM command via ATA
> passthrough?

I'm afraid I don't know how to do that (my SCSI / (S)ATA knowledge is
less than zero).  If there's a page where I can educate myself about how
to send the TRIM command via ATA passthrough I'd appreciate it.  (Aside:
>From my looking up, I don't see any ATA equivalent of SCSI's
'sg3_utils'; wonder if there is any.)

Thanks for the response.

-- 
/kashyap
$> hdparm -I /dev/sdc
/dev/sdc:

ATA device, with non-removable media
        Model Number:       Samsung Portable SSD T5                 
        Serial Number:      S3UNNV0K102165T     
        Firmware Revision:  MVT41P1Q
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, 
SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
Standards:
        Used: unknown (minor revision code 0x0039) 
        Supported: 9 8 7 6 5 
        Likely used: 9
Configuration:
        Logical         max     current
        cylinders       16383   16383
        heads           16      16
        sectors/track   63      63
        --
        CHS current addressable sectors:    16514064
        LBA    user addressable sectors:   268435455
        LBA48  user addressable sectors:   976773168
        Logical  Sector size:                   512 bytes
        Physical Sector size:                   512 bytes
        Logical Sector-0 offset:                  0 bytes
        device size with M = 1024*1024:      476940 MBytes
        device size with M = 1000*1000:      500107 MBytes (500 GB)
        cache/buffer size  = unknown
        Form Factor: unknown (0x0006]
        Nominal Media Rotation Rate: Solid State Device
Capabilities:
        LBA, IORDY(can be disabled)
        Queue depth: 32
        Standby timer values: spec'd by Standard, no device specific minimum
        R/W multiple sector transfer: Max = 1   Current = 1
        DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6 
             Cycle time: min=120ns recommended=120ns
        PIO: pio0 pio1 pio2 pio3 pio4 
             Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
        Enabled Supported:
           *    SMART feature set
           *    Power Management feature set
           *    Write cache
           *    Look-ahead
           *    WRITE_BUFFER command
           *    READ_BUFFER command
           *    NOP cmd
           *    DOWNLOAD_MICROCODE
                SET_MAX security extension
           *    48-bit Address feature set
           *    Mandatory FLUSH_CACHE
           *    FLUSH_CACHE_EXT
           *    SMART error logging
           *    SMART self-test
           *    General Purpose Logging feature set
           *    WRITE_{DMA|MULTIPLE}_FUA_EXT
           *    64-bit World wide name
                Write-Read-Verify feature set
           *    WRITE_UNCORRECTABLE_EXT command
           *    {READ,WRITE}_DMA_EXT_GPL commands
           *    Segmented DOWNLOAD_MICROCODE
           *    Gen1 signaling speed (1.5Gb/s)
           *    Gen2 signaling speed (3.0Gb/s)
           *    Gen3 signaling speed (6.0Gb/s)
           *    Native Command Queueing (NCQ)
           *    Phy event counters
           *    READ_LOG_DMA_EXT equivalent to READ_LOG_EXT
                DMA Setup Auto-Activate optimization
           *    Device-initiated interface power management
           *    Software settings preservation
           *    reserved 69[4]
           *    DOWNLOAD MICROCODE DMA command
           *    SET MAX SETPASSWORD/UNLOCK DMA commands
           *    WRITE BUFFER DMA command
           *    READ BUFFER DMA command
           *    Data Set Management TRIM supported (limit 8 blocks)
Logical Unit WWN Device Identifier: 5002538d00000000
        NAA             : 5
        IEEE OUI        : 002538
        Unique ID       : d00000000
Checksum: correct

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