HDPARM(8)                   System Manager's Manual                  HDPARM(8)

       hdparm - get/set SATA/IDE device parameters

       hdparm [options] [device ...]

       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.  Many newer (2008 and later) USB drive enclosures
       now also support "SAT" (SCSI-ATA Command Translation) and therefore may
       also  work  with  hdparm.   E.g. recent WD "Passport" models and recent
       NexStar-3 enclosures.  Some options may work correctly  only  with  the
       latest kernels.

       When  no  options  are  given, -acdgkmur is assumed.  For "Get/set" op-
       tions, a query without the optional  parameter  (e.g.  -d)  will  query
       (get)  the  device state, and with a parameter (e.g., -d0) will set the
       device 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     Get/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     Get/set (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),  ac-
              tive/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 options can be used to ma-
              nipulate the IDE power modes.

       -d     Get/set 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.

              DCO stands for Device Configuration Overlay, a way  for  vendors
              to  selectively disable certain features of a drive.  The --dco-
              freeze option will freeze/lock the current drive  configuration,
              thereby  preventing  software (or malware) from changing any DCO
              settings until after the next power-on reset.

              Query and dump information regarding  drive  configuration  set-
              tings  which  can  be  disabled  by the vendor or OEM installer.
              These settings show capabilities of the  drive  which  might  be
              disabled  by the vendor for "enhanced compatibility".  When dis-
              abled, they are otherwise hidden and will not  show  in  the  -I
              identify  output.  For example, system vendors sometimes disable
              48_bit addressing on large drives, for compatibility  (and  loss
              of  capacity)  with a specific BIOS.  In such cases, --dco-iden-
              tify will show that the drive is 48_bit capable, but -I will not
              show it, and nor will the drive accept 48_bit commands.

              Reset  all  drive  settings, features, and accessible capacities
              back to factory defaults and full  capabilities.   This  command
              will  fail if DCO is frozen/locked, or if a -Np maximum size re-
              striction has also been set.  This is  EXTREMELY  DANGEROUS  and
              will  very  likely  cause massive loss of data.  DO NOT USE THIS

              Use the kernel's "O_DIRECT" flag when  performing  a  -t  timing
              test.  This bypasses the page cache, causing the reads to go di-
              rectly 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.

              VERY  DANGEROUS,  DON'T  EVEN THINK ABOUT USING IT.  This option
              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 imme-
              diately 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 sec-
              tors by relocating them to "spare" sectors reserved by the  fac-
              tory for such.  Control of this feature via the -D option is not
              supported for most modern drives since ATA-4; thus this  command
              may fail.

       -E     Set cd/dvd drive speed.  This is NOT necessary for regular oper-
              ation, as the drive will automatically switch speeds on its own.
              But  if you want to play with it, just supply a speed number af-
              ter the option, usually a number like 2 or 4.  This can be  use-
              ful in some cases, though, to smooth out DVD video playback.

       -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 options.

              This  option  currently  works  only  on ext4 and xfs filesystem
              types.  When used, this must be the only option given.   It  re-
              quires two parameters: the desired file size in kilo-bytes (byte
              count divided by 1024), followed by the  pathname  for  the  new
              file.   It  will  create  a  new file of the specified size, but
              without actually having to write any data  to  the  file.   This
              will  normally  complete very quickly, and without thrashing the
              storage device.

              E.g. Create a 10KByte file: hdparm --fallocate 10 temp_file

              When used, this must be the only option given.   It  requires  a
              file path as a parameter, and will print out a list of the block
              extents (sector ranges) occupied by that file on  disk.   Sector
              numbers  are given as absolute LBA numbers, referenced from sec-
              tor 0 of the physical device rather than from the  partition  or
              filesystem.   This information can then be used for a variety of
              purposes, such as examining the degree of fragmenation of larger
              files,  or  determining appropriate sectors to deliberately cor-
              rupt during fault-injection testing procedures.

              This option uses the new FIEMAP (file extent map)  ioctl()  when
              available,  and  falls back to the older FIBMAP (file block map)
              ioctl() otherwise.  Note  that  FIBMAP  suffers  from  a  32-bit
              block-number  interface,  and  thus not work beyond 8TB or 16TB.
              FIBMAP is also very slow, and does not deal well  with  preallo-
              cated  uncommitted  extents  in  ext4/xfs  filesystems, unless a
              sync() is done before using this option.

              When used, this should be the only option given.  It requires  a
              file path immediately after the option, indicating where the new
              drive firmware should be read from.  The contents of  this  file
              will  be  sent  to the drive using the (S)ATA DOWNLOAD MICROCODE
              command, using either transfer protocol 7 (entire file at once),
              or,  if  the  drive  supports it, transfer protocol 3 (segmented
              download).  This command is EXTREMELY DANGEROUS  and  could  de-
              stroy  both  the drive and all data on it.  DO NOT USE THIS COM-
              MAND.  The --fwdownload-mode3  ,  --fwdownload-mode3-max  ,  and
              --fwdownload-mode7  variations on basic --fwdownload allow over-
              riding automatic protocol detection in favour of forcing  hdparm
              to use a specific transfer protocol, for testing purposes only.

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

       -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.

       -i     Display  the  identification info which the kernel drivers (IDE,
              libata) have stored from boot/configuration time.  This may dif-
              fer  from  the  current information obtainable directly from the
              drive itself with the -I option.  The data returned may  or  may
              not  be current, depending on activity since booting the system.
              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, and  later  edi-

              Issue  an  ATA  IDLE_IMMEDIATE  command, to put the drive into a
              lower power state.  Usually the device remains spun-up.

              Issue an ATA IDLE_IMMEDIATE_WITH_UNLOAD command,  to  unload  or
              park the heads and put the drive into a lower power state.  Usu-
              ally the device remains spun-up.

       -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 option.

       --Iraw <pathname>
              This option dumps the drive's identify data in raw binary to the
              specified file.

              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.

              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.

       -J     Get/set  the  Western Digital (WD) Green Drive's "idle3" timeout
              value.  This timeout controls how  often  the  drive  parks  its
              heads and enters a low power consumption state.  The factory de-
              fault is eight (8) seconds, which is a very poor choice for  use
              with  Linux.   Leaving it at the default will result in hundreds
              of thousands of head load/unload cycles in a very  short  period
              of  time.   The  drive  mechanism  is  only rated for 300,000 to
              1,000,000 cycles, so leaving it at the default could  result  in
              premature  failure, not to mention the performance impact of the
              drive often having to wake-up before doing routine I/O.

              WD supply a WDIDLE3.EXE DOS utility for tweaking  this  setting,
              and you should use that program instead of hdparm if at all pos-
              sible.  The reverse-engineered implementation in hdparm  is  not
              as  complete  as  the  original official program, even though it
              does seem to work on at a least a few drives.  A full power  cy-
              cle  is  required  for any change in setting to take effect, re-
              gardless of which program is used to tweak things.

              A setting of 30 seconds is recommended for Linux use.  Permitted
              values  are  from 8 to 12 seconds, and from 30 to 300 seconds in
              30-second increments.  Specify a value of zero  (0)  to  disable
              the WD idle3 timer completely (NOT RECOMMENDED!).

       -k     Get/set the "keep_settings_over_reset" flag for the drive.  When
              this flag is set, the drive will preserve the -dmu settings over
              a  soft  reset,  (as  done  during the error recovery sequence).
              This option defaults to off, to prevent drive reset loops  which
              could be caused by combinations of -dmu settings.  The -k option
              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/log/messages on most

       -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 (e.g. Syquest, ZIP,
              Jazz..),  and  setting  it  to 0 will unlock the door mechanism.
              Normally, Linux maintains the door locking  mechanism  automati-
              cally, 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 re-
              mounted 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 fea-
              ture is enabled, it typically reduces operating system  overhead
              for  disk  I/O by 30-50%.  On many systems, it also provides in-
              creased 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 Dig-
              ital recommends lower settings of  4  to  8  on  many  of  their
              drives,  due tiny (32kB) drive buffers and non-optimized buffer-
              ing algorithms.  The -i option 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.

              Deliberately create a bad sector (aka.  "media  error")  on  the
              can be useful for testing of device/RAID error  recovery  mecha-
              nisms.  The sector number is given as a (base10) parameter after
              the option.  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  sec-
              tor  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  imme-
              diately (rather than after several retries).  Note also that the
              --repair-sector option can be used to restore (any) bad  sectors
              when they are no longer needed, including sectors that were gen-
              uinely 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  move-
              ments to reduce their noise output.  The possible values are be-
              tween 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  lev-
              els  between  128 and 254.  At the moment, most drives only sup-
              port 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

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

       -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  be-
              tween  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  origi-
              nally  provided operating system for recovery purposes.  Another
              possible use is to hide the true capacity of a very  large  disk
              from a BIOS/system that cannot normally cope with drives of that
              size (eg. most current {2010}  BIOSs  cannot  deal  with  drives
              larger than 2TB, so an HPA could be used to cause a 3TB drive to
              report itself as a 2TB drive).  To change the current max  (VERY
              DANGEROUS, DATA LOSS IS EXTREMELY LIKELY), a new value should be
              provided (in base10) immediately following the -N option.   This
              value  is  specified as a count of sectors, rather than the "max
              sector address" of the drive.  Drives have the concept of a tem-
              porary (volatile) setting which is lost on the next hardware re-
              set, as well as a more permanent (non-volatile) value which sur-
              vives  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 be-
              fore 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  opera-
              tion  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.  Kernel support for -N
              is  buggy for many adapter types across many kernel versions, in
              that an incorrect (too small) max size value  is  sometimes  re-
              ported.   As  of the 2.6.27 kernel, this does finally seem to be
              working on most hardware.

              Offsets to given number of GiB (1024*1024*1024) when  performing
              -t  timings  of device reads.  Speed changes (about twice) along
              many mechanical drives.  Usually the maximum is  at  the  begin-
              ning,  but  not  always.   Solid-state drives (SSDs) should show
              similar timings regardless of offset.

       -p     Attempt to reprogram the IDE interface chipset for the specified
              PIO  mode,  or attempt to auto-tune for the "best" PIO mode sup-
              ported 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 option 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 cau-
              tion!  This feature includes zero protection for the unwary, and
              an  unsuccessful outcome may result in severe filesystem corrup-

       -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 official spec as of ATA-4.

              When using the SAT (SCSI ATA Translation) protocol, hdparm  nor-
              mally  prefers to use the 16-byte command format whenever possi-
              ble.  But some USB drive enclosures don't  work  correctly  with
              16-byte  commands.   This option can be used to force use of the
              smaller 12-byte command format with such  drives.   hdparm  will
              still  revert to 16-byte commands for things that cannot be done
              with the 12-byte format (e.g. sector accesses beyond 28-bits).

       -q     Handle the next option 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 options.

       -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 disal-
              lows write operations on the device.

       -R     Get/set Write-Read-Verify feature, if  the  drive  supports  it.
              Usage:  -R0 (disable) or -R1 (enable).  This feature is intended
              to have the drive firmware automatically read-back any data that
              is written by software, to verify that the data was successfully
              written.  This is generally overkill, and  can  slow  down  disk
              writes by as much as a factor of two (or more).

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

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

       -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.

       -S     Put  the  drive  into  idle  (low-power)  mode, and also set the
              standby (spindown) timeout for the drive.  This timeout 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 sec-
              onds 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.

              For  drives  which  support  reconfiguring of the Logical Sector
              Size, this flag can be used to specify the  new  desired  sector
              size  in  bytes.  VERY DANGEROUS. This most likely will scramble
              all data on the drive.  The specified size must be one  of  512,
              520,  528,  4096, 4160, or 4224.  Very few drives support values
              other than 512 and 4096.

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

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

              For Solid State Drives (SSDs).  EXCEPTIONALLY DANGEROUS. DO  NOT
              USE  THIS OPTION!!  Tells the drive firmware to discard unneeded
              data sectors, destroying any data that  may  have  been  present
              within  them.   This makes those sectors available for immediate
              use by the firmware's garbage collection mechanism,  to  improve
              scheduling  for  wear-leveling  of the flash media.  This option
              expects one or more sector range pairs immediately after the op-
              tion:  an LBA starting address, a colon, and a sector count (max
              65535), with no intervening spaces.  EXCEPTIONALLY DANGEROUS. DO
              NOT USE THIS OPTION!!

              E.g.  hdparm --trim-sector-ranges 1000:4 7894:16 /dev/sdz

              Identical  to  --trim-sector-ranges  above,  except  the list of
              lba:count pairs is read from stdin rather than  being  specified
              on  the  command  line.  This can be used to avoid problems with
              excessively long command lines.  It  also  permits  batching  of
              many more sector ranges into single commands to the drive, up to
              the currently configured transfer limit (max_sectors_kb).

       -u     Get/set the 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  responsive-
              ness and eliminates "serial port overrun" errors.  Use this fea-
              ture 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 par-
              ticular, 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 fea-
              ture of these interfaces (usually a BIOS/CMOS setting)  provides
              a safe fix for the problem for use with earlier kernels.

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

       -V     Display program version and exit immediately.

              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.

              Writes zeros to the specified sector  number.   VERY  DANGEROUS.
              The sector number must be given (base10) after this option.  hd-
              parm will issue a  low-level  write  (completely  bypassing  the
              usual  block  layer read/write mechanisms) to the specified sec-
              tor.  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     Set  the IDE transfer mode for (E)IDE/ATA drives.  This is typi-
              cally 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 option is seldom nec-
              essary 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 option) for the new mode  setting
              to  prevent  loss  and/or corruption of data.  Use this with ex-
              treme 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  multi-
              word DMA, the value used is the desired DMA mode number plus 32.
              for UltraDMA, the value is the desired UltraDMA mode number plus

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

       -Y     Force  an  IDE  drive to immediately enter the lowest power con-
              sumption 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 option.

       -z     Force a kernel re-read of the partition table of  the  specified

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

       ATA Security Feature Set

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

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

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

              Prompt  for the --security PWD rather than getting from the com-
              mand line args.  This avoids having passwords show up  in  shell
              history or in /proc/self/cmdline during execution.

       --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 ap-
              plicable  drive  password  is  selected  with  the --user-master
              switch (default is "user" password).  No other options are  per-
              mitted on the command line with this one.

       --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.  Use the special password NULL to set an empty
              password.  The applicable drive password is  selected  with  the
              --user-master switch (default is "user" password) and the appli-
              cable security mode with the --security-mode switch.   No  other
              options are permitted on the command line with this one.

       --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 (default is "user" password).  No other options are  per-
              mitted on the command line with this one.

       --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.   Use  the  special  password  NULL to represent an empty
              password.  The applicable drive password is  selected  with  the
              --user-master switch (default is "user" password).  No other op-
              tions are permitted on the command line with this one.

       --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 (default is "user" password).  No other
              options are permitted on the command line with this one.

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

       --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

              OWN RISK.


       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 ev-
       erything before experimenting!

       Some options (e.g. -r for SCSI) may not work with old kernels as neces-
       sary ioctl()'s were not supported.

       Although this utility is intended primarily for use with SATA/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  inter-

       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 in-
       deed 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 suc-
       ceed  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  com-
       mands that way.

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

       The disable Seagate auto-powersaving code is courtesy of Tomi Leppikan-

       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.

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

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

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

Version 9.58                     October 2018                        HDPARM(8)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2024 Hurricane Electric. All Rights Reserved.