Ubuntu Manpage: hdparm - get/set SATA/IDE device parameters

NAME

       hdparm - get/set SATA/IDE device parameters

SYNOPSIS

       hdparm [options] [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.   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.

OPTIONS

When no options are given, -acdgkmur is assumed. For "Get/set" options, 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), 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 options can be used to manipulate 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-freeze
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.

--dco-identify
Query and dump information regarding drive configuration settings 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
disabled, 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-identify will show that the drive is 48_bit capable, but -I will not show it,
and nor will the drive accept 48_bit commands.

--dco-restore
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 restriction has also been set. This is EXTREMELY DANGEROUS
and will very likely cause massive loss of data. DO NOT USE THIS COMMAND.

--direct
Use the kernel's "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 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
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
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 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. This can be
useful 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.

--fallocate
This option currently works only on ext4 and xfs filesystem types. When used, this
must be the only option given. It requires two parameters: the desired file size
in kibibytes (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 10 kibibyte file: hdparm --fallocate 10 temp_file

--fibmap
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 sector 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 fragmentation of larger files, or determining appropriate sectors to
deliberately corrupt 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 8 TB or
16 TB. FIBMAP is also very slow, and does not deal well with preallocated
uncommitted extents in ext4/xfs filesystems, unless a sync() is done before using
this option.

--fwdownload
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 destroy both the drive and all data on it.
DO NOT USE THIS COMMAND. The --fwdownload-mode3 , --fwdownload-mode3-max , and
--fwdownload-mode7 variations on basic --fwdownload allow overriding 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 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).

-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 differ 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 editions.

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

--idle-unload
Issue an ATA IDLE_IMMEDIATE_WITH_UNLOAD command, to unload or park the heads and
put the drive into a lower power state. Usually 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.

--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. Note
that some information will be incomplete, as the drive LOG PAGES are unavailable
when --Istdin is used.

--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.

-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 default 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 possible. 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 cycle is
required for any change in setting to take effect, regardless 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 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 (e.g., 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 (32 KiB) drive buffers and non-optimized buffering 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.

--make-bad-sector
Deliberately create a bad sector (aka. "media error") on the disk. EXCEPTIONALLY
DANGEROUS. DO NOT USE THIS OPTION!! This can be useful for testing of device/RAID
error recovery mechanisms. 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 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 option 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 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 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. 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 (e.g., most current {2010} BIOSs cannot deal
with drives larger than 2 TB, so an HPA could be used to cause a 3 TB drive to
report itself as a 2 TB 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 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. 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 reported. As of the 2.6.27 kernel, this does finally seem
to be working on most hardware.

--offset
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 beginning, 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 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 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 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 official spec as of ATA-4.

--prefer-ata12
When using the SAT (SCSI ATA Translation) protocol, hdparm normally prefers to use
the 16-byte command format whenever possible. 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 disallows 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).

--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 option. 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 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 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 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 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.

--set-sector-size
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. Eg. hdparm --set-sector-size 4096 /dev/sdb

-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.

-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.

--trim-sector-ranges
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 option: 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

--trim-sector-ranges-stdin
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 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.

-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.

--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 option. 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 Set the IDE transfer mode for (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
option 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 option) 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 option.

-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
option.

-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.

ATA Security Feature Set

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

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

--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 options are permitted on the command line with this
one.

--security-prompt-for-password
Prompt for the --security PWD rather than getting from the command 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 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.

--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 applicable
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 permitted 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 options 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-unlock, --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

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 (e.g., -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 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 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,  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
       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.