HDPARM(8) System Manager's Manual HDPARM(8)
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 de-
fault). 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 set-
tings 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 re-
striction 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 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 in-
dication 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 in-
correctly 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 opera-
tion, 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 op-
eration 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 re-
quires 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 with-
out 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 un-
committed 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 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 re-
ports 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 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. 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.
--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 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 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 cor-
rect system operation with a chosen set of configuration set-
tings. 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 sys-
tems).
-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 dri-
ves 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 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 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 Digital rec-
ommends lower settings of 4 to 8 on many of their drives, due
tiny (32 KiB) drive buffers and non-optimized buffering algo-
rithms. The -i option can be used to find the maximum setting
supported by an installed drive (look for MaxMultSect in the out-
put). 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 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 sector
boundary. Some very recent drives (2008) may support the new
WRITE_UNCORRECTABLE_EXT command, which works for any LBA48 sec-
tor. 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. How-
ever, 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 --re-
pair-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 me-
dia).
-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 lev-
els (quiet / fast), while others may have different levels be-
tween 128 and 254. At the moment, most drives only support 3 op-
tions, 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 op-
erating 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 spec-
ified 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 be-
cause 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 ini-
tially, 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 hard-
ware.
--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 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 caution! This
feature includes zero protection for the unwary, and an unsuc-
cessful 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 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 disallows
write operations on the device.
-R Get/set Write-Read-Verify feature, if the drive supports it. Us-
age: -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 (com-
pletely 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 se-
tups. 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 sup-
port the control of this feature by pin 11 of the SATA power con-
nector. 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 ac-
tivity) before turning off the spindle motor to save power. Un-
der 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 pe-
culiar. A value of zero means "timeouts are disabled": the de-
vice will not automatically enter standby mode. Values from 1 to
240 specify multiples of 5 seconds, yielding timeouts from 5 sec-
onds 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 pur-
poses. 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 pur-
poses. 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 ex-
pects 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
--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 exces-
sively long command lines. It also permits batching of many more
sector ranges into single commands to the drive, up to the cur-
rently 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 tol-
erate the increased I/O latencies possible when this feature is
enabled, resulting in massive filesystem corruption. In particu-
lar, 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. hd-
parm 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 er-
ror).
-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 se-
lect simple mode 1 DMA transfers. With systems which support Ul-
traDMA burst timings, -X udma2 is used to select UltraDMA mode2
transfers (you'll need to prepare the chipset for UltraDMA be-
forehand). Apart from that, use of this option is seldom neces-
sary 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 Ul-
traDMA, 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 consump-
tion 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 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 one.
--security-prompt-for-password
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 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 applic-
able security mode with the --security-mode switch. No other op-
tions 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 pass-
word. 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-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
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 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-
faces.
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 prob-
lem. Despite the segfault it is often still possible to run two in-
stances 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 Leppikan-
gas(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.
Version 9.65 Sep 2022 HDPARM(8)
Generated by dwww version 1.16 on Tue Dec 16 04:10:28 CET 2025.