I played with spindown and APM settings of my Samsung discs and now they spin down every minute. I want to disable it, but it seems it does not accept any of the spindown time or APM values. Nothing works, it's all the same.

Please help what values should be proper for it. I do not want it to spin down at all.

/dev/sda:

ATA device, with non-removable media
    Model Number:       SAMSUNG HD154UI                         
    Serial Number:      S1Y6J1KZ206527      
    Firmware Revision:  1AG01118
Standards:
    Used: ATA-8-ACS revision 3b 
    Supported: 7 6 5 4 
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: 2930277168
    Logical/Physical Sector size:           512 bytes
    device size with M = 1024*1024:     1430799 MBytes
    device size with M = 1000*1000:     1500301 MBytes (1500 GB)
    cache/buffer size  = unknown
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: 60
    Recommended acoustic management value: 254, current value: 0
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6 udma7 
         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
            Automatic Acoustic Management feature set
       *    48-bit Address feature set
       *    Device Configuration Overlay feature set
       *    Mandatory FLUSH_CACHE
       *    FLUSH_CACHE_EXT
       *    SMART error logging
       *    SMART self-test
            Media Card Pass-Through
       *    General Purpose Logging feature set
       *    64-bit World wide name
       *    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
       *    NCQ priority information
            DMA Setup Auto-Activate optimization
            Device-initiated interface power management
       *    Software settings preservation
       *    SMART Command Transport (SCT) feature set
       *    SCT Long Sector Access (AC1)
       *    SCT LBA Segment Access (AC2)
       *    SCT Error Recovery Control (AC3)
       *    SCT Features Control (AC4)
       *    SCT Data Tables (AC5)
Security: 
    Master password revision code = 65534
        supported
    not enabled
    not locked
        frozen
    not expired: security count
        supported: enhanced erase
    326min for SECURITY ERASE UNIT. 326min for ENHANCED SECURITY ERASE UNIT.
Logical Unit WWN Device Identifier: 50024e900300cca3
    NAA     : 5
    IEEE OUI    : 0024e9
    Unique ID   : 00300cca3
Checksum: correct

I have the very same disc which I did not "tuned" and it does not spin. But I do not know where to read the settings from. The hdparm only shows this:

    Advanced power management level: 60
    Recommended acoustic management value: 254, current value: 0

Edit: It seems the issue was tuned daemon in RHEL6. It was too aggressive, I turned off disc tuning and it seems they are no longer spinning down.