sudo hdparm --user-master m --security-unlock "                                " /dev/sda

ATA device, with non-removable media
    Model Number:       HGST HTS541075A9E680
    Serial Number:      130723JD13001B02LK3A
    Firmware Revision:  JA2OA560
    Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6; Revision: ATA8-AST T13 Project D1697 Revision 0b
Standards:
    Used: unknown (minor revision code 0x0028)
    Supported: 8 7 6 5
    Likely used: 8
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:  1465149168
    Logical  Sector size:                   512 bytes
    Physical Sector size:                  4096 bytes
    Logical Sector-0 offset:                  0 bytes
    device size with M = 1024*1024:      715404 MBytes
    device size with M = 1000*1000:      750156 MBytes (750 GB)
    cache/buffer size  = 8192 KBytes (type=DualPortCache)
    Form Factor: 2.5 inch
    Nominal Media Rotation Rate: 5400
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 = 16  Current = 16
    Advanced power management level: 254
    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
       *    Security Mode feature set
       *    Power Management feature set
            Write cache
       *    Look-ahead
       *    Host Protected Area feature set
       *    WRITE_BUFFER command
       *    READ_BUFFER command
       *    NOP cmd
       *    DOWNLOAD_MICROCODE
       *    Advanced Power Management feature set
            Power-Up In Standby feature set
       *    SET_FEATURES required to spinup after power up
            SET_MAX security extension
       *    48-bit Address feature set
       *    Device Configuration Overlay 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
       *    IDLE_IMMEDIATE with UNLOAD
       *    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)
       *    Native Command Queueing (NCQ)
       *    Host-initiated interface power management
       *    Phy event counters
       *    Idle-Unload when NCQ is active
       *    NCQ priority information
            Non-Zero buffer offsets in DMA Setup FIS
       *    DMA Setup Auto-Activate optimization
            Device-initiated interface power management
            In-order data delivery
       *    Software settings preservation
       *    SMART Command Transport (SCT) feature set
       *    SCT Write Same (AC2)
       *    SCT Error Recovery Control (AC3)
       *    SCT Features Control (AC4)
       *    SCT Data Tables (AC5)
Security:
    Master password revision code = 65534
        supported
        enabled
        locked
    not frozen
    not expired: security count
        supported: enhanced erase
    Security level high
    164min for SECURITY ERASE UNIT. 166min for ENHANCED SECURITY ERASE UNIT.

/dev/sda:
 Issuing SECURITY_UNLOCK command, password="                               ", user=master
SECURITY_UNLOCK: Input/output error