Provided by: hdparm_8.9-3ubuntu3_i386 bug

NAME

       hdparm - get/set SATA/ATA device parameters

SYNOPSIS

       hdparm [ flags ] [device] ..

DESCRIPTION

       hdparm  provides  a command line interface to various kernel interfaces
       supported by the Linux SATA/PATA/SAS "libata" subsystem and  the  older
       IDE  driver  subsystem.   Some options may work correctly only with the
       latest kernels.

OPTIONS

       When no flags are given, -acdgkmur is assumed.  For Get/Set options,  a
       query  without  an  optional  parameter (e.g., -d) will query (get) the
       drive state, and with a parameter (e.g., -d0) will set the drive state.

       -a     Get/set sector count for filesystem (software) read-ahead.  This
              is used to improve performance  in  sequential  reads  of  large
              files,  by prefetching additional blocks in anticipation of them
              being needed by the running task.  Many IDE drives also  have  a
              separate  built-in  read-ahead  function,  which  augments  this
              filesystem (software) read-ahead function.

       -A     Get/set the IDE drive´s read-lookahead feature  (usually  ON  by
              default).  Usage: -A0 (disable) or -A1 (enable).

       -b     Get/set bus state.

       -B     Set Advanced Power Management feature, if the drive supports it.
              A low value means aggressive power management and a  high  value
              means better performance.  Possible settings range from values 1
              through 127 (which permit spin-down), and values 128 through 254
              (which  do  not  permit spin-down).  The highest degree of power
              management is attained with a setting of 1, and the highest  I/O
              performance  with a setting of 254.  A value of 255 tells hdparm
              to disable Advanced Power Management  altogether  on  the  drive
              (not all drives support disabling it, but most do).

       -c     Query/enable (E)IDE 32-bit I/O support.  A numeric parameter can
              be  used  to  enable/disable  32-bit  I/O   support:   Currently
              supported  values  include 0 to disable 32-bit I/O support, 1 to
              enable 32-bit data  transfers,  and  3  to  enable  32-bit  data
              transfers   with  a  special  sync  sequence  required  by  many
              chipsets.   The  value  3  works  with  nearly  all  32-bit  IDE
              chipsets, but incurs slightly more overhead.  Note that "32-bit"
              refers to data  transfers  across  a  PCI  or  VLB  bus  to  the
              interface  card only; all (E)IDE drives still have only a 16-bit
              connection over the ribbon cable from the interface card.

       -C     Check the current IDE power mode status, which  will  always  be
              one   of   unknown   (drive  does  not  support  this  command),
              active/idle (normal operation), standby (low power  mode,  drive
              has  spun  down),  or  sleeping  (lowest  power  mode,  drive is
              completely shut down).  The -S, -y, -Y, and -Z flags can be used
              to manipulate the IDE power modes.

       -d     Disable/enable the "using_dma" flag for this drive.  This option
              now works with most combinations of drives  and  PCI  interfaces
              which  support DMA and which are known to the kernel IDE driver.
              It is also a good idea to  use  the  appropriate  -X  option  in
              combination  with  -d1  to  ensure  that  the  drive  itself  is
              programmed for the correct DMA mode, although most BIOSs  should
              do this for you at boot time.  Using DMA nearly always gives the
              best performance, with fast I/O throughput and  low  CPU  usage.
              But  there  are  at  least  a few configurations of chipsets and
              drives for which DMA does not make much of a difference, or  may
              even  slow  things  down  (on really messed up hardware!).  Your
              mileage may vary.

       --direct
              Use the kernel O_DIRECT flag when performing a -t  timing  test.
              This  bypasses  the page cache, causing the reads to go directly
              from the drive into hdparm’s buffers, using so-called "raw" I/O.
              In  many cases, this can produce results that appear much faster
              than the usual page cache method, giving a better indication  of
              raw device and driver performance.

       --drq-hsm-error
              VERY  DANGEROUS,  DON’T  EVEN  THINK  ABOUT USING IT.  This flag
              causes hdparm to issue an IDENTIFY command to  the  kernel,  but
              incorrectly marked as a "non-data" command.  This results in the
              drive being left with its  DataReQust(DRQ)  line  "stuck"  high.
              This  confuses  the  kernel  drivers,  and  may crash the system
              immediately with massive data loss.  The option exists  to  help
              in  testing and fortifying the kernel against similar real-world
              drive malfunctions.  VERY DANGEROUS, DO NOT USE!!

       -D     Enable/disable the on-drive defect management  feature,  whereby
              the  drive  firmware  tries  to  automatically  manage defective
              sectors by relocating them to "spare" sectors  reserved  by  the
              factory  for  such.   Control of this feature via the -D flag is
              not supported for most modern  drives  since  ATA-4;  thus  this
              command may fail.

       -E     Set  cdrom  speed.  This is NOT necessary for regular operation,
              as the drive will automatically switch speeds on its  own.   But
              if  you  want  to play with it, just supply a speed number after
              the option, usually a number like 2 or 4.

       -f     Sync and flush the buffer cache for the device  on  exit.   This
              operation  is also performed internally as part of the -t and -T
              timings and other flags.

       --fibmap
              When used, this must be the only flag given.  It requires a file
              path  as  a  parameter,  and will print out a list of the device
              extents (sector ranges) occupied by that file on  disk.   Sector
              numbers  are  given  as  absolute  LBA  numbers, referenced from
              sector  0  of  the  physical  device  (*not*  the  partition  or
              filesystem).  This information can then be used for a variety of
              purposes,   including   determining   appropriate   sectors   to
              deliberately  corrupt during fault-injection testing procedures.

       --fibmap-sector
              When used, this must be the only flag given.  It requires a file
              path  followed  by  a  sector number as parameters.  This sector
              number is given relative to the start of the  file  itself,  not
              the device.  hdparm will scan the device extents occupied by the
              file, and print out the absolute LBA  number  of  the  requested
              sector of the file.  This LBA number is referenced from sector 0
              of the physical device (not the partition or filesystem).   This
              LBA  value can then be used for a variety of purposes, including
              determining an appropriate sector to deliberately corrupt during
              fault-injection testing procedures.

       -F     Flush  the  on-drive  write  cache  buffer (older drives may not
              implement this).

       -g     Display the drive geometry (cylinders, heads, sectors), the size
              (in sectors) of the device, and the starting offset (in sectors)
              of the device from the beginning of the drive.

       -h     Display terse usage information (help).

       -i     Display the identification info that was obtained from the drive
              at  boot  time,  if  available.  This is a feature of modern IDE
              drives, and may not be supported by  older  devices.   The  data
              returned  may or may not be current, depending on activity since
              booting the system.  However, the current multiple  sector  mode
              count  is  always  shown.  For a more detailed interpretation of
              the identification info, refer to AT  Attachment  Interface  for
              Disk  Drives  (ANSI ASC X3T9.2 working draft, revision 4a, April
              19/93).

       -I     Request identification info directly from the  drive,  which  is
              displayed in a new expanded format with considerably more detail
              than with the older -i flag.

       --Istdin
              This is a special variation on the -I option,  which  accepts  a
              drive  identification block as standard input instead of using a
              /dev/hd* parameter.  The format of this block  must  be  exactly
              the  same as that found in the /proc/ide/*/hd*/identify "files",
              or that produced by the --Istdout option described below.   This
              variation  is  designed  for  use  with collected "libraries" of
              drive identification information, and can also be used on  ATAPI
              drives  which may give media errors with the standard mechanism.
              When --Istdin is used, it must be the *only* parameter given.

       --Istdout
              This option dumps the drive’s identify data in hex to stdout, in
              a format similar to that from /proc/ide/*/identify, and suitable
              for later use with the --Istdin option.

       -k     Get/set the keep_settings_over_reset flag for the  drive.   When
              this flag is set, the driver will preserve the -dmu options over
              a soft reset, (as done  during  the  error  recovery  sequence).
              This  flag  defaults  to off, to prevent drive reset loops which
              could be caused by combinations of -dmu settings.  The  -k  flag
              should  therefore  only be set after one has achieved confidence
              in correct system operation with a chosen set  of  configuration
              settings.   In practice, all that is typically necessary to test
              a configuration (prior to using -k) is to verify that the  drive
              can  be  read/written,  and that no error logs (kernel messages)
              are generated in the process (look in /var/adm/messages on  most
              systems).

       -K     Set  the  drive´s  keep_features_over_reset  flag.  Setting this
              enables the drive to retain the settings for -APSWXZ over a soft
              reset  (as  done  during  the error recovery sequence).  Not all
              drives support this feature.

       -L     Set the drive´s doorlock flag.  Setting this to 1 will lock  the
              door  mechanism of some removable hard drives (eg. Syquest, ZIP,
              Jazz..), and setting it to 0 will  unlock  the  door  mechanism.
              Normally,   Linux   maintains   the   door   locking   mechanism
              automatically, depending  on  drive  usage  (locked  whenever  a
              filesystem  is  mounted).  But on system shutdown, this can be a
              nuisance if the root partition is on a removable disk, since the
              root  partition is left mounted (read-only) after shutdown.  So,
              by using  this  command  to  unlock  the  door  after  the  root
              filesystem  is  remounted  read-only,  one  can  then remove the
              cartridge from the drive after shutdown.

       -m     Get/set sector count for multiple sector I/O on  the  drive.   A
              setting  of  0 disables this feature.  Multiple sector mode (aka
              IDE Block Mode), is a feature of most modern  IDE  hard  drives,
              permitting  the  transfer of multiple sectors per I/O interrupt,
              rather than the usual  one  sector  per  interrupt.   When  this
              feature  is  enabled,  it  typically  reduces  operating  system
              overhead for disk I/O by  30-50%.   On  many  systems,  it  also
              provides  increased  data throughput of anywhere from 5% to 50%.
              Some drives, however (most notably the WD Caviar  series),  seem
              to  run  slower  with  multiple  mode enabled.  Your mileage may
              vary.  Most drives support the minimum settings of 2, 4,  8,  or
              16  (sectors).   Larger settings may also be possible, depending
              on the drive.  A setting of 16  or  32  seems  optimal  on  many
              systems.  Western Digital recommends lower settings of 4 to 8 on
              many of their drives, due tiny (32kB)  drive  buffers  and  non-
              optimized buffering algorithms.  The -i flag can be used to find
              the maximum setting supported by an installed  drive  (look  for
              MaxMultSect  in  the  output).   Some  drives  claim  to support
              multiple mode, but lose  data  at  some  settings.   Under  rare
              circumstances,  such  failures  can result in massive filesystem
              corruption.

       --make-bad-sector
              Deliberately create a bad sector (aka.  "media  error")  on  the
              disk.   EXCEPTIONALLY  DANGEROUS.   DO NOT USE THIS FLAG!!  This
              can  be  useful  for  testing  of  device/RAID  error   recovery
              mechanisms.   The sector number is given as a (base10) parameter
              after the flag.  Depending on the device, hdparm will choose one
              of  two  possible  ATA  commands for corrupting the sector.  The
              WRITE_LONG works on most drives,  but  only  up  to  the  28-bit
              sector boundary.  Some very recent drives (2008) may support the
              new WRITE_UNCORRECTABLE_EXT command, which works for  any  LBA48
              sector.   If  available,  hdparm  will use that in preference to
              WRITE_LONG.  The WRITE_UNCORRECTABLE_EXT command itself presents
              a  choice  of how the new bad sector should behave.  By default,
              it will look like any other bad sector, and the drive  may  take
              some  time  to retry and fail on subsequent READs of the sector.
              However, if a single letter f is prepended immediately in  front
              of  the  first digit of the sector number parameter, then hdparm
              will issue a "flagged" WRITE_UNCORRECTABLE_EXT, which causes the
              drive  to  merely  flag the sector as bad (rather than genuinely
              corrupt it), and  subsequent  READs  of  the  sector  will  fail
              immediately (rather than after several retries).  Note also that
              the --repair-sector flag  can  be  used  to  restore  (any)  bad
              sectors  when  they are no longer needed, including sectors that
              were genuinely bad (the drive will likely remap those to a fresh
              area on the media).

       -M     Get/set Automatic Acoustic Management (AAM) setting. Most modern
              harddisk  drives  have  the  ability  to  speed  down  the  head
              movements to reduce their noise output.  The possible values are
              between 0 and 254. 128 is the most quiet (and therefore slowest)
              setting and 254 the fastest (and loudest). Some drives have only
              two levels (quiet /  fast),  while  others  may  have  different
              levels  between  128  and  254.  At the moment, most drives only
              support 3 options,  off,  quiet,  and  fast.   These  have  been
              assigned  the  values  0, 128, and 254 at present, respectively,
              but integer space has been incorporated  for  future  expansion,
              should this change.

       -N     Get/set  max  visible  number of sectors, also known as the Host
              Protected Area setting.  Without a parameter,  -N  displays  the
              current  setting,  which  is  reported  as two values: the first
              gives the current max sectors setting, and the second shows  the
              native  (real)  hardware  limit  for  the  disk.  The difference
              between these two values indicates how many sectors of the  disk
              are currently hidden from the operating system, in the form of a
              Host Protected Area (HPA).  This area is often used by  computer
              makers  to  hold  diagnostic  software,  and/or  a  copy  of the
              originally provided operating system for recovery purposes.   To
              change  the  current max (VERY DANGEROUS, DATA LOSS IS EXTREMELY
              LIKELY), a new value should be provided (in base10)  immediately
              following  the  -N  flag.  This value is specified as a count of
              sectors, rather than the "max  sector  address"  of  the  drive.
              Drives  have the concept of a temporary (volatile) setting which
              is lost on the next hardware reset, as well as a more  permanent
              (non-volatile) value which survives resets and power cycles.  By
              default, -N affects only the temporary (volatile)  setting.   To
              change  the  permanent (non-volatile) value, prepend a leading p
              character immediately before  the  first  digit  of  the  value.
              Drives  are supposed to allow only a single permanent change per
              session.  A hardware reset (or power cycle) is  required  before
              another  permanent  -N  operation  can  succeed.   Note that any
              attempt to set this value may fail if the disk is being accessed
              by other software at the same time.  This is because setting the
              value requires a pair of back-to-back drive commands, but  there
              is  no  way  to  prevent  some other command from being inserted
              between them by the kernel.  So if it fails initially, just  try
              again.

       -n     Get or set the "ignore write errors" flag in the driver.  Do NOT
              play with this without grokking the driver source code first.

       -p     Attempt to reprogram the IDE interface chipset for the specified
              PIO  mode,  or  attempt  to  auto-tune  for  the "best" PIO mode
              supported by the drive.  This feature is supported in the kernel
              for  only  a  few "known" chipsets, and even then the support is
              iffy at best.  Some IDE chipsets are unable  to  alter  the  PIO
              mode  for  a single drive, in which case this flag may cause the
              PIO mode for both drives to be set.  Many IDE  chipsets  support
              either  fewer  or more than the standard six (0 to 5) PIO modes,
              so the exact speed setting that  is  actually  implemented  will
              vary   by   chipset/driver  sophistication.   Use  with  extreme
              caution!  This feature includes zero protection for the  unwary,
              and  an  unsuccessful  outcome  may  result in severe filesystem
              corruption!

       -P     Set the maximum sector count for the drive´s  internal  prefetch
              mechanism.   Not  all  drives  support  this feature, and it was
              dropped from the offical spec as of ATA-4.

       -q     Handle the next flag quietly, suppressing normal output (but not
              error  messages).   This  is  useful for reducing screen clutter
              when running from system startup scripts.  Not applicable to the
              -i or -v or -t or -T flags.

       -Q     Get or set the device’s command queue_depth, if supported by the
              hardware.  This only works with 2.6.xx (or later)  kernels,  and
              only  with device and driver combinations which support changing
              the queue_depth.  For SATA disks, this  is  the  Native  Command
              Queuing (NCQ) queue depth.

       -r     Get/set   read-only  flag  for  the  device.   When  set,  Linux
              disallows write operations on the device.

       --read-sector
              Reads from the specified sector number, and dumps  the  contents
              in  hex  to  standard  output.   The sector number must be given
              (base10) after this flag.  hdparm will issue  a  low-level  read
              (completely   bypassing   the   usual   block  layer  read/write
              mechanisms) for the specified  sector.   This  can  be  used  to
              definitively  check  whether a given sector is bad (media error)
              or not (doing so through the usual mechanisms can sometimes give
              false positives).

       --repair-sector
              This is an alias for the --write-sector flag.  VERY DANGEROUS.

       -R     Register  an  IDE  interface (DANGEROUS).  See the -U option for
              more information.

       -s     Enable/disable the power-on in standby feature, if supported  by
              the   drive.   VERY  DANGEROUS.   Do  not  use  unless  you  are
              absolutely 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
              powered-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.

       -S     Set the standby (spindown) timeout for the drive.  This value is
              used by the drive to determine how long to wait  (with  no  disk
              activity)  before  turning  off the spindle motor to save power.
              Under such circumstances, the drive  may  take  as  long  as  30
              seconds  to  respond  to  a  subsequent disk access, though most
              drives are much quicker.  The encoding of the timeout  value  is
              somewhat   peculiar.   A  value  of  zero  means  "timeouts  are
              disabled": the device will not automatically enter standby mode.
              Values  from  1  to 240 specify multiples of 5 seconds, yielding
              timeouts from 5 seconds to 20 minutes.  Values from 241  to  251
              specify from 1 to 11 units of 30 minutes, yielding timeouts from
              30 minutes to 5.5 hours.  A value of 252 signifies a timeout  of
              21  minutes. A value of 253 sets a vendor-defined timeout period
              between 8 and 12 hours, and the value 254 is reserved.   255  is
              interpreted as 21 minutes plus 15 seconds.  Note that some older
              drives may have very different interpretations of these  values.

       -T     Perform  timings  of  cache  reads  for benchmark and comparison
              purposes.  For meaningful  results,  this  operation  should  be
              repeated  2-3  times  on  an otherwise inactive system (no other
              active processes) with at least a couple of  megabytes  of  free
              memory.   This  displays  the speed of reading directly from the
              Linux buffer cache without disk  access.   This  measurement  is
              essentially  an  indication  of the throughput of the processor,
              cache, and memory of the system under test.

       -t     Perform timings of device reads  for  benchmark  and  comparison
              purposes.   For  meaningful  results,  this  operation should be
              repeated 2-3 times on an otherwise  inactive  system  (no  other
              active  processes)  with  at least a couple of megabytes of free
              memory.  This displays the speed of reading through  the  buffer
              cache  to  the  disk  without  any  prior caching of data.  This
              measurement is an indication of how fast the drive  can  sustain
              sequential  data  reads  under  Linux,  without  any  filesystem
              overhead.  To ensure accurate measurements, the buffer cache  is
              flushed during the processing of -t using the BLKFLSBUF ioctl.

       -u     Get/set  interrupt-unmask  flag  for  the drive.  A setting of 1
              permits the driver to unmask other interrupts during  processing
              of   a   disk   interrupt,   which   greatly   improves  Linux´s
              responsiveness and eliminates "serial port overrun" errors.  Use
              this feature with caution: some drive/controller combinations do
              not tolerate the increased  I/O  latencies  possible  when  this
              feature  is enabled, resulting in massive filesystem corruption.
              In particular, CMD-640B and  RZ1000  (E)IDE  interfaces  can  be
              unreliable  (due  to  a  hardware flaw) when this option is used
              with kernel versions earlier than  2.0.13.   Disabling  the  IDE
              prefetch  feature  of  these  interfaces  (usually  a  BIOS/CMOS
              setting) provides a safe  fix  for  the  problem  for  use  with
              earlier kernels.

       -U     Un-register an IDE interface (DANGEROUS).  The companion for the
              -R option.  Intended for use with hardware made specifically for
              hot-swapping  (very  rare!).   Use  with  knowledge  and extreme
              caution as this can easily hang  or  damage  your  system.   The
              hdparm  source  distribution includes a ´contrib´ directory with
              some user-donated scripts for hot-swapping on the UltraBay of  a
              ThinkPad 600E.  Use at your own risk.

       -v     Display some basic settings, similar to -acdgkmur for IDE.  This
              is also the default behaviour when no flags are specified.

       --verbose
              Display extra diagnostics from some commands.

       -w     Perform a device reset (DANGEROUS).  Do NOT use this option.  It
              exists for unlikely situations where a reboot might otherwise be
              required to get a confused drive back into a useable state.

       --write-sector
              Writes zeros to the specified sector  number.   VERY  DANGEROUS.
              The  sector  number  must  be  given  (base10)  after this flag.
              hdparm will issue a low-level write  (completely  bypassing  the
              usual  block  layer  read/write  mechanisms)  to  the  specified
              sector.  This can be used to force  a  drive  to  repair  a  bad
              sector (media error).

       -W     Get/set the IDE/SATA drive´s write-caching feature.

       -x     Tristate device for hotswap (DANGEROUS).

       -X     Set  the IDE transfer mode for newer (E)IDE/ATA drives.  This is
              typically used in combination with -d1 when enabling DMA to/from
              a drive on a supported interface chipset, where -X mdma2 is used
              to select multiword DMA mode2 transfers and -X sdma1 is used  to
              select  simple mode 1 DMA transfers.  With systems which support
              UltraDMA burst timings, -X udma2  is  used  to  select  UltraDMA
              mode2 transfers (you´ll need to prepare the chipset for UltraDMA
              beforehand).  Apart from  that,  use  of  this  flag  is  seldom
              necessary  since  most/all  modern  IDE  drives default to their
              fastest PIO transfer mode at power-on.  Fiddling with  this  can
              be  both  needless and risky.  On drives which support alternate
              transfer modes, -X can be used to switch the mode of  the  drive
              only.   Prior  to  changing the transfer mode, the IDE interface
              should be jumpered or programmed (see -p flag) for the new  mode
              setting  to  prevent  loss  and/or corruption of data.  Use this
              with extreme caution!  For  the  PIO  (Programmed  Input/Output)
              transfer  modes  used by Linux, this value is simply the desired
              PIO mode number plus 8.  Thus, a value of 09 sets PIO mode1,  10
              enables  PIO  mode2,  and  11  selects  PIO  mode3.   Setting 00
              restores the drive´s "default" PIO mode, and 01 disables  IORDY.
              For multiword DMA, the value used is the desired DMA mode number
              plus 32.  for UltraDMA, the value is the desired  UltraDMA  mode
              number plus 64.

       -y     Force   an   IDE  drive  to  immediately  enter  the  low  power
              consumption standby mode, usually causing it to spin down.   The
              current power mode status can be checked using the -C flag.

       -Y     Force  an  IDE  drive  to  immediately  enter  the  lowest power
              consumption sleep mode, causing it to shut down  completely.   A
              hard  or soft reset is required before the drive can be accessed
              again (the Linux IDE driver will automatically handle issuing  a
              reset  if/when  needed).   The  current power mode status can be
              checked using the -C flag.

       -z     Force a kernel re-read of the partition table of  the  specified
              device(s).

       -Z     Disable  the  automatic power-saving function of certain Seagate
              drives (ST3xxx models?), to prevent them  from  idling/spinning-
              down at inconvenient times.

       -H     Read  the  temperature  from some (mostly Hitachi) drives.  Also
              reports if the temperature is within operating  condition  range
              (this  may not be reliable). Does not cause the drive to spin up
              if idle.

       ATA Security Feature Set

       These switches are DANGEROUS to experiment with,  and  might  not  work
       with every kernel.  USE AT YOUR OWN RISK.

       --security-help
              Display terse usage info for all of the --security-* flags.

       --security-freeze
              Freeze the drive´s security settings.  The drive does not accept
              any security commands  until  next  power-on  reset.   Use  this
              function  in combination with --security-unlock to protect drive
              from any attempt to set a new password. Can be used  standalone,
              too.  No other flags are permitted on the command line with this
              one.

       --security-unlock PWD
              Unlock the drive, using password PWD.  Password is given  as  an
              ASCII  string  and  is  padded with NULs to reach 32 bytes.  The
              applicable drive password is  selected  with  the  --user-master
              switch.   No  other flags are permitted on the command line with
              this one.  THIS FEATURE IS EXPERIMENTAL AND NOT WELL TESTED. USE
              AT YOUR OWN RISK.

       --security-set-pass PWD
              Lock  the  drive, using password PWD (Set Password) (DANGEROUS).
              Password is given as an ASCII string and is padded with NULs  to
              reach  32 bytes.  The applicable drive password is selected with
              the --user-master switch and the applicable security  mode  with
              the --security-mode switch.  No other flags are permitted on the
              command line with this one.  THIS FEATURE  IS  EXPERIMENTAL  AND
              NOT WELL TESTED. USE AT YOUR OWN RISK.

       --security-disable PWD
              Disable drive locking, using password PWD.  Password is given as
              an ASCII string and is padded with NULs to reach 32 bytes.   The
              applicable  drive  password  is  selected with the --user-master
              switch.  No other flags are permitted on the command  line  with
              this one.  THIS FEATURE IS EXPERIMENTAL AND NOT WELL TESTED. USE
              AT YOUR OWN RISK.

       --security-erase PWD
              Erase (locked) drive, using password PWD (DANGEROUS).   Password
              is  given as an ASCII string and is padded with NULs to reach 32
              bytes.  The applicable  drive  password  is  selected  with  the
              --user-master  switch.   No  other  flags  are  permitted on the
              command line with this one.  THIS FEATURE  IS  EXPERIMENTAL  AND
              NOT WELL TESTED. USE AT YOUR OWN RISK.

       --security-erase-enhanced PWD
              Enhanced  erase  (locked) drive, using password PWD (DANGEROUS).
              Password is given as an ASCII string and is padded with NULs  to
              reach  32 bytes.  The applicable drive password is selected with
              the --user-master switch.  No other flags are permitted  on  the
              command  line  with  this one.  THIS FEATURE IS EXPERIMENTAL AND
              NOT WELL TESTED. USE AT YOUR OWN RISK.

       --user-master USER
              Specifies which password (user/master) to select.   Defaults  to
              master.   Only  useful  in  combination  with --security-unlock,
              --security-set-pass,  --security-disable,  --security-erase   or
              --security-erase-enhanced.
                      u       user password
                      m       master password

              THIS  FEATURE  IS  EXPERIMENTAL AND NOT WELL TESTED. USE AT YOUR
              OWN RISK.

       --security-mode MODE
              Specifies which security mode (high/maximum) to  set.   Defaults
              to high.  Only useful in combination with --security-set-pass.
                      h       high security
                      m       maximum security

              THIS  FEATURE  IS  EXPERIMENTAL AND NOT WELL TESTED. USE AT YOUR
              OWN RISK.

FILES

       /etc/hdparm.conf

BUGS

       As noted above, the -m sectcount and -u 1 options should be  used  with
       caution  at  first,  preferably on a read-only filesystem.  Most drives
       work well with these features, but a few drive/controller  combinations
       are  not  100%  compatible.   Filesystem corruption may result.  Backup
       everything before experimenting!

       Some options (eg. -r for  SCSI)  may  not  work  with  old  kernels  as
       necessary ioctl()´s were not supported.

       Although  this  utility  is intended primarily for use with (E)IDE hard
       disk devices, several of the options are also valid (and permitted) for
       use  with  SCSI  hard  disk  devices  and  MFM/RLL  hard  disks with XT
       interfaces.

       The Linux kernel up until 2.6.12 (and probably  later)  doesn´t  handle
       the  security  unlock and disable commands gracefully and will segfault
       and in some cases even  panic.  The  security  commands  however  might
       indeed  have  been  executed  by  the drive. This poor kernel behaviour
       makes the PIO data security commands rather useless at the moment.

       Note that the "security erase" and  "security  disable"  commands  have
       been  implemented  as  two  consecutive  PIO data commands and will not
       succeed on a locked drive because the second command will not be issued
       after the segfault.  See the code for hints how patch it to work around
       this problem. Despite the segfault it is often still  possible  to  run
       two  instances  of  hdparm  consecutively  and  issue the two necessary
       commands that way.

AUTHOR

       hdparm has been written by Mark Lord  <mlord@pobox.com>,  the  original
       primary  developer  and maintainer of the (E)IDE driver for Linux, with
       suggestions from many netfolk.

       The  disable  Seagate  auto-powersaving  code  is  courtesy   of   Tomi
       Leppikangas(tomilepp@paju.oulu.fi).

       Security freeze command by Benjamin Benz, 2005.

       PIO  data out security commands by Leonard den Ottolander , 2005.  Some
       other parts by Benjamin Benz and others.

SEE ALSO

       http://www.t13.org/ Technical Committee T13 AT  Attachment  (ATA/ATAPI)
       Interface.

       http://www.serialata.org/ Serial ATA International Organization.

       http://www.compactflash.org/ CompactFlash Association