I have a desktop PC, that dubs as a RAID-6 server. When I don't need the RAID-related stuff, I'd like to spin off all the hard drives involved in RAID (I hate the noise). Unfortunately, even if everything is stopped, the system probes the drives from time to time causing the hard drives to spin up.

From the hdaparm man page one can read, that issuing commands like hddparm -s /dev/sdc can prevent the disk from ever spinning up again... unless the motherboard supports it:

   -s     Enable/disable  the power-on in standby feature, if supported by
          the drive.  VERY DANGEROUS.  Do not use  unless  you  are  abso‐
          lutely  certain  that both the system BIOS (or firmware) and the
          operating system kernel (Linux >= 2.6.22)  support  probing  for
          drives  that  use this feature.  When enabled, the drive is pow‐
          ered-up in the standby mode to allow the controller to  sequence
          the  spin-up of devices, reducing the instantaneous current draw
          burden when many drives share a power supply.  Primarily for use
          in  large RAID setups.  This feature is usually disabled and the
          drive is powered-up in the active mode  (see  -C  above).   Note
          that  a  drive may also allow enabling this feature by a jumper.
          Some SATA drives support the control of this feature by  pin  11
          of the SATA power connector. In these cases, this command may be
          unsupported or may have no effect.

I still don't understand, what is the worst scenario if the hard drive or motherboard don't support it. Does it mean, that the hard drive will be bricked?

Or will it be enough to take the hard drive to a friend, who happens to have compatible motherboard which would map the spinned-down hard drives, to re-enable it?

Another question: What exactly features should my hard drive support? My hard drive seems to support Power-Up In Standby feature set, which may not be the same as power-on in standby feature mentioned by the man.

How can I check necessary features it in for motherboard? What name does this feature have?

The hdparm -I /dev/sdc:

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
        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
   *    SMART error logging
   *    SMART self-test
   *    General Purpose Logging feature set
   *    64-bit World wide name
   *    {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)
   *    Host-initiated interface power management
   *    Phy event counters
   *    NCQ priority information
   *    DMA Setup Auto-Activate optimization
   *    Software settings preservation
   *    SMART Command Transport (SCT) feature set
   *    SCT Write Same (AC2)
   *    SCT Features Control (AC4)
   *    SCT Data Tables (AC5)
        unknown 206[12] (vendor specific)
        unknown 206[13] (vendor specific)

RAID combines the existing drives into a "superdrive". There aren't "drives that can be turned off because they aren't being used" (unless the RAID is a separate set from the drive from which the machine boots/with the operating system).

  • I know. But sometimes I don't need any part of the array. And this is what I write about. The array is on completely separate set of hdds than the rest of the system. – Adam Ryczkowski Feb 12 '14 at 12:14

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